200+ WHP NA build

[Tony D]

" I don't think there is a turnkey setup with the throttle-bodies, control-unit, sensors, pumps, cable etc. needed to put FI on an originally carbureted car"

 

Boss EFI makes a system meant for cars without a fuel return line especially muscle cars and is a complete Fuel SYSTEM kit involving carb conversion body, fuel pump, sensors ecu etc. It's good to 500HP utilizing an OEM style long and short term fuel trim to 'self tune' the ECU with it's onboard WBO2 for best engine performance with minimal technical involvement of the owner. You can get it without carb body (usually a four barrel, but they do have triple strombergs as an option) to use DCOE Style ITB's. As shown above sourcing of ITB's is from several different sources and is a function of what you are willing to pay. "Turnkey" never comes cheap, and if you think you will bolt on tripples and turn the key to the tune of 200HP we are again entering fantasyland.

 

If that technical complexity scares you, farm it out.

[JMortensen]

If you aren't comfortable with EFI, don't use it. Shouldn't be too hard to hit your hp numbers without it. It will make the low speed driveability much better as Tony says, but there is no need to use EFI to get 200 whp, and a 200 whp motor doesn't have to be strung out like a crack ***** to make that kind of power.

[Bob_H]

The big take-away that seems to be missed by the OP - we aren't saying you would cruise around at 7500 rpm, or that you can't do it - but rather you don't NEED to do 7500rpm for the goals. You can do it, at a $$$ expense, ok, maybe $$$$ expense..

But what is coming out clearly from your posts is a partial focus on 7500 rpm, or the rpm period, not the power. We live in a world where a Honda can turn 8-9000 rpm and people seem to think if you don't pull big RPM numbers, you aren't really producing big power w/o race gas, 13:1 CR, monster cams, etc... Take a look at aircraft engines for proof of that - but that is not the main point. Decide if you want a set HP, or if you just want a set RPM. While they are related - they are not tied. 200 whp is fairly straight forward to achieve - and with driveability. It won't be cheap, but not much is when your talking bigger power from a 30-40 year old powerplant design.

Again, 200 whp is not hard to do - 7500 is not out of the realm of posiblity, but will drive up your cost for a much smaller gain in power compared to other approaches.

Strokers don't "fall on their face" at 6500 rpm. The Camshaft falls on its face or the tuning falls on its face or the combined setup falls on its face - its not running out of steam because it has a diesel crank and longer rods.

I just bought Dan Baldwin's car that put 255+ to the rear wheels - uh oh, 3.1L stroker, 7000 rpm. The weak point in his,(now my), motor? The cast KA24E pistons. Thats the reason for the approx 7k self imposed redline and honestly it doesn't need any more than that.

I will state - the combo for 255 rwhp was worked on for a long time, uses a no longer available sunbelt prep'd head/camshaft and is a great combo of parts to end up with that power. You can get similar today from Rebello for a price..

Streetable and he drove it to EVERY event he tracked - most of them several hours. Not as streetable as a 175 rwhp car, but I tracked it and it was very easy to drive. Its the combo of parts and the tuning, not the rpm per say.

Bottom line - figure out if its the RPM or the power you want. 7k and 200 rwhp are achievable w/o burning your bank down and knowing super secret know-how or owning super rare parts.

-Bobby

 

 

 

Basically a mild stroker build without the long crank (to give me my 7500 RPM redline without radical porting).

know I could get the whp easily with a 3.1 build, but they all seem to max out around 6500 RPM or less

[Tony D]

Scott B. of Group Z Sports Car Club (see photos of his car in the intersection on the 'How to make a 240Z Safer' thread...) ran a Slovers-Ported head with an Iskendarian Cam and SU Carburettors to turn 182HP to the rear wheels on a cast-piston 0.040" overbore flat-topped piston 6500rpms power peak L28 with MASSIVE low-end torque. It's another example of Bob H's example. Originally there was a long list and 'internet overbuild' involved in his car. In the end:

 

SU's man...

 

Now, when he started he was looking into EFI, looking into triple Mikuinis, looking into all sorts of stuff. In the end a set of tired SU's ran that car to 182 and with the power coming on the way it did, a set of 44's would EASILY push that engine to over 200 at the rear wheels.

 

Like Bob H says, there is some obsession with an RPM point. Scott scratches his head when our 2.0 made 205 to the rear wheels. So did someone else when a 3.2 and Mikuini 44's ran 224 at 5800rpms peak! It's the proper matching of parts that makes real power, not som magic bullet of rpms or displacement. What is wanted can be reached using stock components (if not a engine swap from a particular, specific stock Datsun!)

 

This isn't rocket science, it isn't something that needs exotic parts. RPM's will get you power, but at what cost? And why?

 

If there TRULY is a Horsepower Goal---then where you make it won't matter. Gear accordingly.

 

Power in an L-Engine is, has been, and always will be in the Head. RPM's may give you more, but the money you spend on the head in proper preparation will make a versatile bolt-on for almost any combination you choose to run underneath it.

 

Put $3200 in the bottom end and you just cost yourself $3200 for a dedicated setup.

 

Put $1500-2400 into the proper head work and you got something that can work on several subsequent builds, and if you do it right when you get those forged pistons in there later on...it won't be 7500 that is the limit if you've done your headwork right!

 

Believe it or not, we ran the exact same head on a 320HP L28, and on a 205HP L20A. Yeah, we lost horsepower because we didn't have all the compression we 'should' have had on the L20A...but know what? We also didn't want to spend $2400 for another freakin' head, either!

 

That stance has recently changed, though...

 

Street engines and weekend warriors are frequently overbuilt money pits with people building from a list of internet parts everybody says they 'need' when building a performance engine. Many times it's merely "parrot droppings"---guys just prattling on about what you 'need' because they read it in a magazine or online someplace.

 

You can make a LOT of power without spending a fortune on bottom end internals and your longevity will not suffer in any discernable, measurable way.

 

Hell, you want 200HP just go get a stock Eurospec 280ZXT engine....DONE! Stock. Cast Pistons. 300,000 mile reliability.

 

You don't need forged in any 200HP engine.

 

You do in a 7500rpm engine.

 

The two are different animals. There is absolutely no requirement to twist the engine that tight to get only 200HP. It's turning for the sake of turning.

 

And that VO7 7500rpm limit? I'd disregard that as well...

Edited September 14, 2011 by Tony D

[middleagedcrazy]

But what is coming out clearly from your posts is a partial focus on 7500 rpm, or the rpm period, not the power. We live in a world where a Honda can turn 8-9000 rpm and people seem to think if you don't pull big RPM numbers, you aren't really producing big power w/o race gas, 13:1 CR, monster cams, etc... Take a look at aircraft engines for proof of that - but that is not the main point. Decide if you want a set HP, or if you just want a set RPM. While they are related - they are not tied. 200 whp is fairly straight forward to achieve - and with driveability. It won't be cheap, but not much is when your talking bigger power from a 30-40 year old powerplant design.

 

I am the original poster, and I didn't just pull numbers out of the air; I actually did a lot of thinking about what I wanted and my options for how to get there. I wanted to avoid getting into debates about torque-vs-hp and whether dynamic compression is real and such other rants, so I went light on the theory. I'll try to explain my thinking without killing any sacred cows... Before I go too far, let me say this is all approximation; its back-of-the-envelope numbers to get to a starting point.

 

The 200 whp goal is based on having noticeably more power than the RSX-S I drive to work every morning. I'd be happy to get more, but I don't want to sacrifice too much drivability by going too big on cams or carbs.

 

Max crank torque from an NA engine depends mostly on displacement and a little on CR. In a well behaved engine, torque is pretty flat from around 3000RPM up to the power peak where torque starts to drop. A 10:1 CR will generate about 60 ft-lbs/liter (my apologies to the metric purists for those units). Increasing CR by 1 point will increase torque by about 4% (to 63 ft-lb/l) , and dropping it 1 point decreases torque about 4% (to 57 ft-lb/l). You shouldn't assume that trend is linear - as CR goes up it yields smaller and smaller increases in max torque. Again, this is an approximation, but its close for lots of real world engines. Note that the cam doesn't have much impact on max-torque; only on the shape of the torque curve. A big cam can move the point where torque drops off to a higher RPM, and so makes more power.

 

I want to run on pump gas, so a CR around 10 is as high as I want to go. 60 ft-lb/liter * 2.8 liter = 168 ft-lbs . The relation between torque and hp is well known, HP = torque * RPM / 5252. Nothing magic here, just physics. Use some algebra: (250 hp / 168 ft-lb) * 5252 = 7800 RPM! This is a ridiculous redline, but its what you need to turn to actually make 250 crank hp on a 10:1 L28. I don't consider that realistic, so if I want to get close, I need more displacement and maybe a little more compresson. Clearly a stroker build would meet my needs. 60 ft-lb/l * 3.1 liter = 186 ft-lb. (250/186) * 5252 = 7000 RPM. Bump up the compression on a stroker to 11:1 and you can get 250 crank hp at 6500 RPM. I'd prefer to split the difference and shoot for 2.9 liters displacement, a 10.3 CR and a redline somewhere around 7-7.5K RPM.

 

What I didn't say was that a 3.1 can't rev; what I was trying to say was at this hp level (250 crank) the stroker is flowing all the air it needs to around 6500RPM. Reving higher can make even more power, but also requires more flow capability. I suspect the big reason most strokers don't rev past 6500 RPM has nothing to do with long crank throws or rod/stroke ratios; its that they're running 40mm triples and small cams that can't flow enough air to feed 3.1 liters past 6500 rpm. No matter what combination of displacement and RPM you take to get to that hp level, you need a head that can flow the air needed for that power level.

 

Anyways, lots of things to think about - thanks again for the real world feedback.

Don

[Tony D]

Theorists also said the mean pistons speed of the top fuel engines and the speed they will reach is impossible...

 

Making statements like CR will give you X and Y results is foolish. Same as projecting crank torque to a mythical rpm power peak.

 

Your biggest problem is your discounting of what proper breathing does for torque, and how much more it makes compared to your examples. If you don't think a camshaft makes a huge difference in peak torque go back to school on that one. Yes, it influences the curve--guys say all you can do it move it up or down. Wrong! If you have a COMPETENT cam grinder, and discuss your flow in the head, the lift and valve events occur to maximuze YOUR combination (you don't buy a cam off the shelf when a custom ground one specifically tailored to YOUR application is a whole $100!!!!)

 

The 3.2 I quoted was running 44 Mikunis and 36 boosters. It wasn't the induction, nor the flow of the head, it was his cam that limited his output. 5800 rpms was the peak, and it was 'lazy'. It was a store-bought cam, one of those 'advertised' units. Gave up a lot IMHO, it cost the same to have one ground, why not have done it right in the first place?

 

All the theoretical calculators say that 44's with 36's should be up a bit higher than that, and make more power at a higher RPM. But with the off the shelf cam he had, that is how it worked out.

 

Theory is good to a point, but I wouldn't bet my power production from the L-Series on it. Some combinations of parts work exceedingly well together, others don't. Scott's engine with 40's on it should easily pick up 20HP if not more from the reduced pumping losses on the intake side alone. Putting him within 24 HP of a 3.2 with 44's--you would THINK the big carbs and 3-400CC's would be worth more than that on the Benchracing Theoretical Scale!

 

AGAIN, it's the combination of parts, not picking numbers out of the air that are based on nothing more than theory. It doesn't work like that except on the benchracing interwebs.

 

In Scott's case, he came up with similar assumptions as you did. In the end talking with a head porter and a cam grinder he came up with a 2.8 at 0.040" over that twisted a set of SU's to 182 hp at the rear wheels at 6500 rpms or less with less CR than he thought he 'needed'.

 

How does that fit in your calculations? The CR was Califorina-Pump Gas 91 No-Ping. Meaning less than you are stating you 'need' to get that power.

 

At 11:1 what does at 2L need to turn to make 205HP?

 

Theory is good to a point. You need to discard it when you get to the real world and find examples that tell you there is more than textbook calculations to factor into the equation.

[Lazeum]

I agree with Tony.

 

 

I had a L28 combo made with off the shelf parts: stock overbore flat top pistons (0.5mm), N42 head giving me a CR around 10:1 with “stage 2†MSA cam (Schneider 274°/274°).

 

I ran 40DCOE Weber with 32mm chokes tuned with O2 WB sensor showing good AFR.

 

Engine was running good but timing wasn’t so good due to poor part matching.

 

 

I decided to trust head builder so I’ve changed the head and the cam on my setup, CR has been decreased to almost 9:1. Head is ported and unshrouded. Cam is a custom grind to meet my engine specs and especially my needs; I wanted a fat torque curve over peak HP.

 

 

It’s amazing the difference it makes. Engine torque has increased very significantly whereas displacement remains the same, CR has been decreased and engine is not even tuned yet.

 

Timing can now be setup as it should without fearing ping; it means also you should be able to play with timing to get what you're after. I’m now limited to my Carb chokes, 32mm is definitely too small – they don’t match my setup.

 

 

Something as well to bring to the discussions is the feeling. With Triple carbs or ITB and a good exhaust, I believe car feels also much quicker than it really is; noise becomes really nice, you’ll get addicted very quickly.

 

 

With same HP but more torque than your RSX, the Z will feel way quicker and rewarding.

 

 

[z-ya]

Stock N47 head (no porting), .460 lift / 280 deg duration cam, stock springs and valves, cast flat tops:

 

 

Solid line is dual TB SU manifold. Dotted is stock EFI manifold.

 

 

180WHP is easy, streetable, and reliable.

Edited September 14, 2011 by z-ya

[middleagedcrazy]

Making statements like CR will give you X and Y results is foolish. Same as projecting crank torque to a mythical rpm power peak.

 

 

...

At 11:1 what does at 2L need to turn to make 205HP?

 

Theory is good to a point. You need to discard it when you get to the real world and find examples that tell you there is more than textbook calculations to factor into the equation.

 

Tony,

 

I think I said it several times; I made some estimates to come up with a starting point, but those estimates are based on a fair amount of real observation. Once a cylinder of a given volume has compressed a given mass of air/fuel mix and the spark plug fires, how the air/fuel got there doesn't matter much. Cylinder pressure is going to go up and force the piston down, transmitting power to the wheels in the process. How much of the heat energy gets turned into work depends largely on the expansion ratio of the cylinder (which also happens to be the CR). I've been reading car magazines for 30 years and looking at dyno sheets posted on the web a few more - 60 ft-lb/liter (1 ft-lb per inch) is a pretty good guess for a production auto engine. Well tuned engines - where fuel delivery and ignition is just right - seem to make a tiny bit (1-2%) more. Increasing the CR gives relatively small increases; I've looked at theoretical efficiency charts in my old thermodynamics book that predict about 4% difference between 10:1 and 11:1, or about 63 ft-lb/liter for 11:1. Project out to 13:1 and its about 10% more than 10:1; call it 66 ftl-lb/l, a well tuned 13:1 motor might make it to 68. The few 13:1 engines I can find data for fit this prediction fairly well: L88 chevy: 7L x 67 ft-lb/L = 469 ft-lb. At 6000 RPM, that works out to 535 hp, which agrees reasonably well with published info (for whatever its worth).

 

I can see how a poorly designed or tuned engine can make less torque/liter than this, but not really more. A tuned intake can bump up the torque at a particular RPM, but its at most a few percent. The one thing that screws up this simple view of the world is VTEC engines with multi-path intakes. By playing games with valve-timing and plenum-length/volume they can put a big torque/liter bump at mid-range RPMs - much more than than my model predicts - but the torque at the power peak is still pretty close to that predicted here.

 

Lets look at your 11:1 example. I'll assume its well tuned and guess a little on the high-side: 64 ft-lb/L; thats a max torque of 128 ft-lb, and the algebra tells us (205/128) * 5252 = 8400 RPM. How close did I get?

 

I understand these are estimates, and they ignore a lot. Just throwing in forged pistons won't get an L28 to 7500 RPM; there has to be headwork, the right cam and carbs/FI else it doesn't matter how long you hold the gas down - you're not going to top 6K. If these parts aren't right the engine won't make anything close to my estimates. These are the details I'm hoping to work out.

 

Don

 

[Gollum]

1 Fast Z's 3.1 doesn't seem to die out at 6500... seems to pull quite nicely all the way to 8k... I bet he's making a whole lot more than 200 to the wheels too...

 

I personally feel you can expect a lot more than just 60lbs per liter out of a mild L engine. As you can see from the STOCK N47 head above it's making around 64lbs per liter TO THE WHEELS!

 

I'm all about theory, but you have to base your theory off of what experience you might have access to. We have case after case after case of L engines that easily reach 100+hp per liter when prepped right. We have case after case of motors built on a budget that rev to 8k.

 

You've already gotten the mass of opinion from people on this board who have experience seeing builds actually WORK, unless some other forums with people that slap on a cam and exhaust and expect some magical HP increase... Many of those out there that aren't making power are failing to do some basic research before purchasing parts. You (the OP) seem to be interested in doing things right, and even spending a little bit of money to do it right.

 

Now, for my .02 cents of how you should spend your money (because that's why we're all on here right? )

 

I think of lot of what you're looking for is response as much as high RPM limit. As such, I'd say get a L24 block, and bore it out and use K24 pistons with OEM comparable clearances for street friendly warm up and performance. Use whatever head you'd like to go for the compression you'd like, probably at least 9.0, and probably no more than 10.5 depending on what cam you'd like to run. You're wanting good wide power so I'd stick with a milder cam with milder CR, so less than 10. The most important thing though, is to take this head to a good head machinist, and clean up the chamber. Unshroud the valves and clean up the seat to chamber area. Regarding the port I wouldn't worry too much since your power goals are conservative. Some basic work might be desirable, as outlined by BRAAP here in the stickies. Odds are you gain all the extra flow capacity you need just from the chamber work which is one often overlooked area of head flow. Then just port match your intake and the port work is done. Find the cam you want, and run a valvetrain setup accordingly to assure you don't float the valves but don't wear the cam beyond what's needed. This usually isn't a problem in the L crowd, but I've seen people upgrade valves to way beyond required and suffer from needing constant valve adjustments as often as oil changes. Make sure to pair the engine to a lightweight flywheel as well. And if you feel like spending the money, have your machinist take any weight possible off the KA24 pistons. There's always areas of OEM pistons that aren't structural areas that can be taken out a little, and every ounce you save on piston mass will reduce stress on the bottom end and increase revability. You'll see even in the OEM realm how much piston weight matters as you start to demand more power per liter without force induction. Just go look at the new Ford Coyote pistons. Now just tune the sucker and you're done. Your choice of EFI or carb shouldn't make any difference with the importance of tuning the engine. This is one area that's often overlooked by people who don't see the power they were going after. Find out what others have run, what their setup was, and how it worked for them, and what their AFR looked like on the dyno.

 

I'll say this because if there's one thing I've really taken away from hybridZ it's this. System System System. Build a SYSTEM, not a collection of nice parts. This is the lesson learned with people like MONZTER or even the high HP turbo builds like Tim's. The system needs to match. Everything from intake runner diameter, cam, exhaust primary, carb jet, etc. Don't overlook a single aspect and you'll be rewarded with WAY more power than most people expect for a given setup.

 

I'd bet you could do this all for around $3k easily enough as long as you find good honest people to do the machine work and are willing to do some work yourself. You'll have around the same money invested as those doing an engine swap, but you'll also have a pretty mean machine with an awesome sound, and the power you were after. You can spend far more on other areas of the car, so I personally think it's a pretty realistic budget for an overall build.

[josh817]

Surprised Tony hasn't just default answered you "Put money in envelope, mail to Rebello, wait a few weeks, engine on doorstep".

 

I think there is more than enough here to get you going. This is the point where you don't do what I did; keep rambling and thinking into it. Instead, go out and DO IT. My goals are more extreme but I mope around asking what I need to do which yields me absolutely nothing... for the past... well almost a year!

 

As for that 7000RPM thing. You probably don't need forged pistons with one thing in mind, that you don't linger in 7000RPM territory long. Hell, break away from a light and wind that ***** up, I don't think that instant you will regret not having forged. I'm thinking more like if you're tracking the car and constantly seeing 7000RPM or spending a decent amount of time in that range (aka going down a long straight). I'm saying this because I've done it on my 3.1L, and kept doing it from when I was 16-19 years old. Not a single problem except for one thing and that was one day I slowly pulled through 7000RPM instead of banging through it and grabbing a gear. I threw a rocker arm but luckily I didn't scratch the cam lobe or lose pieces down the front cover. Took 5 minutes to get back on and another 10 minutes to set my valve lash on all 12 rockers.

 

Don't forget, lower gearing can be a make believe power addition.

 

From http://datsunzgarage.com/ his L28 with SU's, 10:1 comp., geared lower but not extremely low, I don't think he said forged pistons, doing the regular old 7000RPM fun run down the road, dynoed @ 168HP:

 

Whats this a 2.9L? Running a VO7 crank, stock 280 pistons, mild crane cam, 10.7:1 comp., twin SU's, 4.11 rear end, revs to 8000RPM, best run is a 12.8 sec quarter mile:

 

First video, you can visit his website and read up, second video he has more if you want to check them out. He posts details about the setup and sometimes even more stuff in the comments he leaves.

 

Oh and again Tony is right (I hate when that happens, how does he do that?), VO7 crank not revving.... forget about that. Video I posted on the first page are both VO7 cranks I believe of course with lots of time and money dumped into the motor, but it doesn't have to be that way.

Edited September 14, 2011 by josh817

[Bob_H]

Ok good Will Hunting... (a little movie reference for those that don't get it)

 

I know you are the OP but I'm not a name caller - and you've done a great job telling us who have motors that put out big HP and more than what you want - why its not theoretically possible.

 

There is an excellent quote my Dad often used on me and others when I was growing up:

 

"A Man convinced against his will is of the same opinion still".

 

You've convinced yourself that your right. You have the theoretical/reading/interpreting to back up what you have come to believe. You came and asked us - we told you what works, what we have done that works, but your coming back with your theoretical/reading/etc..on why we can't be right.

 

Your convinced and its not our job to convince you why your wrong, but yours to figure out why we are getting these results that don't match with your theoretical hypothesis.

 

Again, we have told you what HAS worked - not why it theoretically won't/can't work. Your coming back with why it shouldn't work and your idea/theory should. Its only your money in the long run - not ours...

-Bob

 

 

I've been reading car magazines for 30 years and looking at dyno sheets posted on the web a few more - 60 ft-lb/liter (1 ft-lb per inch) is a pretty good guess for a production auto engine

 

Of note on an edit:

 

60 ft-lb/liter (1 ft-lb per inch) is a pretty good guess for a production auto engine. Well tuned engines - where fuel delivery and ignition is just right - seem to make a tiny bit (1-2%) more.

 

So with my LS2 in my 94 RX-7 which is a 6.0L motor - should only make 360 ft-lb of torque, or maybe 375ft-lb if the fuel delivery and ignition are just right. However, it put 475 lb-ft of torque to the WHEELS. pump gas, 11:1 CR.

That means the figures you have arrived at based on reading/internet lurking just aren't correct. My motor in the RX-7 put 50% more lb-ft of torque at the flywheel vs your example,(540lb-ft at the flywheel).

We can find all kinds of examples to vary much more than 1-2% beyond your model. This indicates its not an accurate model/theory.

Edited September 14, 2011 by Bob_H

[Leon]

You know, we can play the bench racing game, quote magazine and internet numbers all we want but it won't get you anywhere. You need a defined set of parameters which will constrain your design. Once the needs are nailed down, it becomes very easy to accomplish your goals.

 

You state, and I infer, that your needs are almost purely subjective; the car must feel and sound fast, but must be smooth at idle and around town. Hell, slap on some triples and twice pipes, and you're good to go! There is no need for most of the stuff you list in your first post. I have a ton of fun with my triple carb'd, twice pipe, stock cam L24 that put down 121 hp/136 lb-ft (before the new exhaust and advanced timing, need to go back to dyno). It's smooth, torquey and makes all the right sounds. Just consider this, before delving further into this internet automotive gobbledegook.

[johnc]

60 ft-lb/liter (1 ft-lb per inch) is a pretty good guess for a production auto engine. Well tuned engines - where fuel delivery and ignition is just right - seem to make a tiny bit (1-2%) more.

 

No. Way low. My 3L L6 engine made a max of 275 ft. lbs. of torque and had at least 200 ft. lbs. from 4,000 to 7,200 rpms. 13.6 to 1 CR, Motec M48, V07 crank, JE pistons, 65mm TB, 4.5L plenum, 7.5" tapered intake runners, custom cam, lots of head work, etc. It was not a production engine and ran on Sunoco GT Supreme race fuel.

[BluDestiny]

This might be one iteration of the L20 that Tony is talking about.

[Gollum]

I just realized something rather humorous about this thread. The sub-description says "and still driveable????"

 

Can everyone with a 250+whp NA L motor who street drive their cars please stand up?

 

Seems like most people that come on here asking questions are shooting for 300+hp, not a mere 200.... That's rather funny to me.

[Tony D]

For Lazeum:

"Something as well to bring to the discussions is the feeling. With Triple carbs or ITB and a good exhaust, I believe car feels also much quicker than it really is; noise becomes really nice, you’ll get addicted very quickly. "

 

ABSOLUTELY! My story of the Triple-Carbbed L28 with 87HP that FELT fast as hell but was down on power to stock EFI is up before, and follows exactly what he's saying. The quiet Stock EFI made 147 on the same engine, less the headers! (And it jibes nicely with Leon's ride in his post as well as an old 240 I had long ago...) Feels and Sounds are terrible quantifiers of power to the roadway.

 

As to the 8400 rpms estimate... Well, maybe it had less than we thought... Try it a 9:1 then and not 11:1 (it was the same head from the L28, you can only pop up a 79mm bore piston so far into an 86mm combustion chamber), and I guess the C16 was wasted.

 

Here again, the forest is lost from all the trees. The books all said the Top Fuelers could never make it because the mean piston speed was 'impossible to achieve'... Books are books, and you can read all you want. Reading only accomplishes so much--in this case maybe tired eyes. Doing accomplishes something else, and produces a tangible result.

 

And as Gollums post points out, Irony is biting when a guy is looking for 100less HP than the average post here. There were plenty of 325HP L24's in Japan in the 80's...but they have a different 'driveable' definition than most Americans. Then again, I guess it depends on how you drive!

Edited September 15, 2011 by Tony D

[Gollum]

... Books are books, and you can read all you want. Reading only accomplishes so much--in this case maybe tired eyes. Doing accomplishes something else, and produces a tangible result.

 

You're making me want to get off my butt and do something Tony!

 

You know, I have a freshen'ed spare E88 sitting in my garage, and a tired L28E that wants to be rebuilt. I'm really temped to bake my head and add some aluminum for some quench pads and then do some basic machine work just to get my hands dirty. It's already got nissan comp springs... Just need a good cam and voila.... And I'd do all this "just because"

[Tony D]

It's the best reason there ever was!

[middleagedcrazy]

No. Way low. My 3L L6 engine made a max of 275 ft. lbs. of torque and had at least 200 ft. lbs. from 4,000 to 7,200 rpms. 13.6 to 1 CR, Motec M48, V07 crank, JE pistons, 65mm TB, 4.5L plenum, 7.5" tapered intake runners, custom cam, lots of head work, etc. It was not a production engine and ran on Sunoco GT Supreme race fuel.

 

Not to belabor this, but you took a general statement for a production engine (that is: an engine built by a manufacturer for every day use, with a CR around 9-10:1) and tried to apply it to a what is essentially a racing engine. The rest of my text says CR is the major factor affecting torque/liter. 13.6 should give about 12-15% higher torque/L - and all the little tweaks done to a high-performance engine adds a bit more. Call it 70 ft-lb/l, and your 3L should make about 210 ft-lb torque, and 7200 RPM works out to 288 hp (thats at the crank). I don't understand how you got 275 ft-lb at any RPM, but I'd like to learn. What I'm thinking is that a high-overlap cam has a sweet-spot in the RPM range where it combines with the manifold length to give a Veff > 1 and so generates a bump in the torque curve.

 

If you look at Z-ya's vintage-racer-build-up (awesome thread by the way) you see the same thing - the engine is a 2.85L making a fairly flat 72 ft-lb/l, except for a big bump in torque around 6000RPM. I'll be the first to agree, my approximation doesn't work all that well for borderline race engines. I still think the approximation is pretty good for mild-street engines (up to around 11:1).

 

I guess you can drive a 13:1 motor on the street. Back in the muscle car days I knew lots of guys who threw a big cam and bigger Holley on a SBC and they made awesome power - from 5000 to 5500 RPM... Keeping them running at a red light required setting the idle somewhere around 1500RPM and frequent throttle-blips to "clean out" the carb. Not what I want to spend $3000 to achieve. With FI and a good fuel map you can no doubt straighten that all out - I'm still open to FI. I should probably chase down someone in the area with Megasquirt and ITBs and see how they run, I could see being really happy with such a setup.

 

Tony - 205 (crank HP) and 9:1 compression (I'll guess 57 ft-lb/l) works out to 9450 RPM - bet it sounded pretty!

 

Finally, if my estimates are low, the worst thing that happens is I build a motor that makes more power than I had hoped for. That ain't so bad...

 

Thanks again for the info - its what I asked for - I'll let you know what I learn along the way.

 

Don