How much of a horsepower gain would this be?

[Guest ON3GO]

you said you have a Z31.. arent they sohc?

 

mike

[Guest FinalRights]

Yea,I have a Z31,its a V6,so its two cam gears.

[johnc]

Using the L28e:2.5" Exhaust straight through,newer headers,ITB's,Upgraded fuel system,Adjustable Cams,Underdrive Pulleys,Electric radiator fan.

 

Jon,

 

Where did you get individual throttle bodies out of this list? ITB's are air filters (the black foam, red platic ones) unless folks are now throwing around ITB as an acronym. That might be my mistake. Even with individual throttle bodies and no cam, head, or compression work I don't think you'll see much of a horsepower gain.

 

Couple points here... John C.s car was making over 300 at the wheels...

 

278.9 on the Superior Automotive chassis dyno.

[JMortensen]

I have an ITG filter that fits your description John (black foam, red plastic). Never heard of an ITB filter, and when someone says ITB I think individual throttle bodies, but that may not be correct either...

 

Jon

[johnc]

I have an ITG filter

 

You're right, I'm a noob...

[Guest bastaad525]

Johnc how much torque did you put down?

 

I tend to find that high hp N/A L6's usually put down a bit less torque, numerically, than HP, and that their HP peak is usually pretty high. I think this is why many people consider them not to be as friendly for street driving. Turbo L6's always seem to develop a lot more torque than hp, with both peaking pretty low. This tends to make turbo motors 'feel' faster when going all out, but of course, off the boost the turbo feels much more sedate and lazy.

[johnc]

My engine was actually built for a flat torque band.

 

I sacrificed ultimate horsepower for more torque. On the engine dyno the torque peak was 257 ft. lbs. at around 5,500 rpm with over 200 ft. lbs. of torque from 4,100 to 7,200 rpm. Horsepower is about as flat with a peak of 305 at 6,600 rpm and at least 250 hp from 5,250 to 7,400.

 

On the chassis dyno the numbers are peak torque 234 at 5,700 with at least 200 ft. lbs. from 4,300 to 7,100 rpm and peak horsepower of 279 at 6,500 with at least 250 hp from 5,500 to 7,300 rpm.

 

The engine doesn't make much power under 4,000. But from 4,000 to 7,400 it just pulls and pulls. Both Bryan Lampe and Erik Messley who've raced the car have said its a very flexible engine and deceptively fast. You don't feel a big peak in power, which lulls you into thinking you're not going that fast. But then the corners come up real quick.

[Drax240z]

Hmm, maybe I'm a noob, but I think 200rwhp is attainable from a NA L-series without breaking the bank, doing a turbo conversion, or adding NOS... From 1/4mile times I'd say there are a few around me locally, and on this board.

 

Flat top pistons

N42/E31 big valve head - or some other combo in excess of 10:1 compression ratio

Moderately hot cam

Header/2.5" exhaust

Triple 40's

Electronic ignition

Quality ignition system/multispark box

 

Combine it with some decent gearing and you have a FUN car to drive that sounds incredible, and is knocking on the door of 200rwhp.

 

On an aside, according to the calculators (which aren't perfectly accurate) Norm Simpers is making in the area of 270 crank horsepower with dual SU's... He posted a few months back that he had ~$3000 into his entire car. Granted he's often the exception to the rule, but he's shattered the 200rwhp mark. Assuming 15% drivetrain loss he's at 230rwhp.

[JMortensen]

Yep. I think you're right Drax. The one thing I'll point out is that Norm's SU's are not stock. I don't think much over 200hp at the crank is possible with stock SU's.

 

Jon

[Mack]

yeah, norms car has got to be right around 230 to 240rwhp. Go here . granted, this guys L20B only put down 94.4 hp, but if you scroll down, it has the dyno peak readings of a few other cars. a few L28's. 2 of them were in the 160 to 170 rwhp range, and they didnt really have anything special done to them. For factory ratings, datsun did something weird. In all th ZX's, they rated them at the back of the transmission with all accessories running. so, to get WHP, you have to figrue in for the diff. which on the P79 cars, figures right around 125 stock hp at the wheels.

 

these cars are choked exhaust wise and intake. if you did away with the stock systems, and put in a nice cam, with very mild porting and some compression to wake it up, I think you could swing 200rwhp on a decent budget. I guess I'll let you guys know as soon as I get enough cash for my cam! lol i have a maxima N47 head going on a flat top block with mild porting and a planned 256 degree, .491" lift cam. with my port matched, cleaned up P82 intake (no egr) and a nice exhaust system (2.5" mandrel) I think I can pull some decent times. we shall see. perhaps a 60mm TB and my infiniti M30 conversion will help too....

 

McAdam

[Dan Baldwin]

I tend to find that high hp N/A L6's usually put down a bit less torque' date=' numerically, than HP, and that their HP peak is usually pretty high. I think this is why many people consider them not to be as friendly for street driving. Turbo L6's always seem to develop a lot more torque than hp, with both peaking pretty low.[/quote']

 

lb-ft being numerically less than hp is really just a units thing, and basically just means that you're still making at least decent torque above 5252rpm (where lb-ft and hp are numerically equal). Most turbo L6s just aren't tuned for max power, I've seen plenty of dyno runs that end at 6000 or less!

 

Tuning for peak power will always dictate that you move the torque curve up in the rpm range, doesn't really mean you're giving up much if any peak torque.

 

I'm making 220rw lb-ft with 3.1 liters, so 200 lb-ft should be doable with a 2.8. I bet a 200rwhp L28 is attainable without any headwork (other than maybe shaving to get a good CR). That's your easiest/cheapest/quickest path to 200rwhp, I think.

[Guest bastaad525]

Hmm' date=' maybe I'm a noob, but I think 200rwhp is attainable from a NA L-series without breaking the bank, doing a turbo conversion, or adding NOS... From 1/4mile times I'd say there are a few around me locally, and on this board.

 

Flat top pistons

N42/E31 big valve head - or some other combo in excess of 10:1 compression ratio

Moderately hot cam

Header/2.5" exhaust

Triple 40's

Electronic ignition

Quality ignition system/multispark box

 

Combine it with some decent gearing and you have a FUN car to drive that sounds incredible, and is knocking on the door of 200rwhp.

 

On an aside, according to the calculators (which aren't perfectly accurate) Norm Simpers is making in the area of 270 crank horsepower with dual SU's... He posted a few months back that he had ~$3000 into his entire car. Granted he's often the exception to the rule, but he's shattered the 200rwhp mark. Assuming 15% drivetrain loss he's at 230rwhp.[/quote']

 

 

Your 'recipe' is EXACTLY what I built, except running SU's instead of triples, and again, I put down just short of 170rwhp. I dont think the triples would have been worth an extra 30. I was running a nissan 5sp and 3.9 rear end, and it was a fun car for sure, but not nearly fast enough for me, again, best 1/4 time would have been somewhere in the range of a high 14 or 15 flat.

 

Norm IS very much an exception, but it does go to show what you can do if you're willing to get your hands dirty, so to speak. Remember though that a) his motor is a stroker, and we're talking a whole nuther ballpark there vs. just using a regular L28 block and crank, and he did like 99% of the work himself. And it was no small amount of work. As I said earlier and almost any L6 enthusiast will say, all of an L6's power can be found in the head, and Norm did a TON of headwork himself, by hand (I believe he said it took either a couple weeks or a couple months of going at it). If you are knowledgeable, careful, and patient enough to do this kind of thing yourself then yeah you can do a 200rwhp+ motor for relatively cheap, but most people aren't, and end up paying well over $1000 to do that kind of headwork necessary to get that power level.

 

Johnc - your numbers do illustrate my point. Getting good hp and torque peaks on an N/A usually means moving the power band up pretty high, which is why I personally prefer doing a turbo or V8 swap. Driving a car where "The engine doesn't make much power under 4,000. But from 4,000 to 7,400 it just pulls and pulls." just isn't a whole lot of fun on the street driving around town. When driving on the street I seldom want to take it over 3,000rpm, and even in my N/A motor with no headwork and very mild cam, it had just about NO power under 3,000rpm, and really felt like a slug sometimes, but usually it was not too bad, with the 3.9 getting up to 3,000 in a hurry wasn't a problem when I really wanted to scoot. Freeway revs and mileage of course suffered as a result. With the turbo motor boost starts coming on early, and peaks around 2,400, and torque immediately jumps up to about 220ft lbs and stays above 200 to about 5,000 rpm and dropping so slowly that the HP stays almost perfectly flat almost all the way to 6k. Not a wider power band than John's at all, but since it comes on much lower I would think it makes for a better street ride, even with a lower 3.54 rear end the car pretty much just goes when you stomp it. But of course it doesn't go as IMMEDIATELY as a good N/A motor would, but I suspect in a motor tuned like johnc's, cruising on the street below 3,000rpm, if you stomped it it probably wouldn't 'just go' either.

 

Dan - I agree most turbos do hit their hp and torque peaks well below 6000rpm, but then again, so do most N/A L6's that don't have the headwork and cam necessary to bring their power band up into the higher rev's. My N/A 2.9 peaked it's hp pretty close to where my turbo does now in revs, and the couple times I dynoed it there was no point in taking that one above 6k either. You mention that you could do 200rwhp with just shaving the head, but remember, even that in itself can be a lot of work, because now you have to shim the cam towers and try to find/figure out the right size lash pads to keep your valvetrain geometry all correct. If you really want to go N/A, and I hope NOT to open up the can of worms on this one, but I personally feel that taking a P90 head, and shaving it to achieve similiar compression as an N42 head, will net you the best results. No one has proven or disproven this one yet, but the things that make the most sense to me are a) the P90 was the LAST head designed for the L6, and incorporates 10+ years of knowledge learned by Nissan designers who were building L6 heads, and the P90 was used primarily as the head for the turbo motor, which is why it is a lower compression head, however many people agree that if they were designing this head expressly for use in a turbo application, where airflow potential would seem to be more important, it makes sense that it is probably a better flowing head. Lastly it seems to be designed with detonation resistance in mind with 'heart shaped' chambers vs. round chambers on the N42, and I can attest to the fact that my N42 head, 10.3:1 compression motor was definately NOT detonation resistant! Either way, the N42 and P90 are both great performance heads.

 

Again, I can only speak from experience. I don't and cannot do machine shop work myself. Prepping heads or building stroker motors is out of the range of my capabilities, so for me to build anything, I have to pay someone else to do it. I dont know about FinalRights so I can't speak for him. But in my case, where I took two motors, one N/A, one turbo, and invested around $5000 in the labor to rebuild (and build up, in the case of the N/A), install, and tune them, I got way more bang for my buck with the turbo motor. Had I been able to do all the work on those motors myself they would both still have been pretty even cost wise, the N/A might have been a cheaper initial investment, but I would have spent much more of my own time working on the N/A, and still would have ended up with a less powerful motor. Even if final rights can prep a head himself and build up a really good N/A motor he will most likely still end up the same way, even if he spends less. But WHY go to all the trouble when just taking a bone stock turbo motor and dropping it in, the most troublesome part being the wiring which really is not that troublesome at all (we're talking about splicing like 3-6 wires depending on how you do it) and you'd end with a car with much more power and potential for much more than even that with a few upgrades?

 

Given the money and the chance to do it again I would never build up another N/A motor, period.

[JMortensen]

Bastaad, I can say from personal experience that I think triples WOULD have gotten you to 200 hp, properly tuned. I think you overestimate the benefit of headwork and underestimate the restriction caused by the SU's. Example: with my 1st engine and SU's, I could barely get to the 6800 rpm rev limiter, despite the cam and ported head. Same engine build with Mikunis would hit the rev limiter HARD. When I originally got the Mikunis on the old motor, I took my wife out for a ride. She had autox'd on the old motor maybe 5 or 6 times. The carbs made such a HUGE difference that she was SCARED of the car. Took her several autox's before she'd really wind it up again.

 

I agree with Dan and Drax that a shaved head would net 200 hp on the original build this guy was talking about.

 

I'm sorry that you spent so much time and $$$ on a failed NA project, but the project itself is not without merit, and I really think that carbs would have made all the difference for you. Maybe not if you want a low rpm engine, but if you're willing to wind it up there is a lot of performance to be had in an NA buildup.

 

Side note--Bastaad, I like your song Crash a lot. Sent chills down my spine (I think that's the best compliment I can give any music).

 

EDIT--Norm's SU's are NOT STOCK!!!

 

Jon

[johnc]

"The engine doesn't make much power under 4,000. But from 4,000 to 7,400 it just pulls and pulls." just isn't a whole lot of fun on the street driving around town.

 

While my engine is NOT a street engine, a lot more "streetability" can be had if the right gearing is chosen. I'm trying a 4.63 rear gear for autocross and run either a 4.38 or a 4.11 for track events.

 

For my low rpm work I drive my 1964 Continental with the 430 cu. in. engine or my F350 with the 417 cu. in. V10.

[Guest bastaad525]

jmortensen - I know SU's are not great for top end power, but to counter what you're saying I will myself use Norm Simpers as an example. While his SU's are not stock they are modified in ways that any person could easily do themselves. In his case it is definately a case of good head work, together with the diesel crank, that really gets his car moving. I find it very hard to believe that switching to tripples over SU's would have in itself have netted me 30 extra hp at the wheels. Yes it would moved the powerband up higher and would have resulted in a higher hp peak, but 30hp??? I'm thinking more like 10-15 at the most. Whereas I know two guys personally that dynoed and got around 30-40ish hp from having some good head work done (I think the guy that got 40 more also went with a different cam when he had his head done but I dont remember for sure). But both headwork and triples serve basically the same end, which is getting better flow into and out of that head, so yeah they both will benefit quite a bit. But at what cost? I've seen triples go anywhere from $500 for a used set to $1500 for new ones. Not to mention dyno tuning time is NOT an option once they are installed if you ever hope to get the car running right so at least another few hundred dollars right there I would think. Head work, again, is also not cheap. If you look long enough you can pick up a turbo motor with the EFI system or even a whole donor car for the price of the triples alone! The only 'tuning' I've really done on my turbo motor (other than a tune-UP!!!) was installing the boost controller and cranking it! When I dynoed I didn't touch ANYTHING, the mixture was good up until the point where the fuel pump couldn't keep up, and the timing is pretty much set-and-forget. What else is there? With triples or hell even with SU's you have to worry about jetting or jet's and needles and springs and you really gotta sit there and mess with them if you want optimum performance. I WILL say this, my personal experience with stock Nissan EFI systems has also sucked and I do sometimes miss the simplicity of my SU's, but I dont think I'd ever want to mess with triples. Most people have had few or even no problems with stock nissan EFI though.

 

johnc - hell I think even a stock 135hp L28 would feel pretty quick with 4.63 gearing!!! What gear would you consider to be 'street gearing' for your motor though? I imagine it would still be a relatively high numerical gear, and though that may get you by on the street, keeping your power band within easy reach. No fun on the freeways though. Anyways you are definately an extreme, a far cry from this guys desired 200hp so it is kind of a moot point. Don't get me wrong I'm not downplaying your setup at all, actually I used to use your setup as a benchmark to aim for when I'd dream of what I wanted to do with my N/A motor... very very impressive what you've got there. How much would you say you've invested in the build of the motor alone?

[Guest bastaad525]

jmortensen - and by the way thank you for the compliment

[JMortensen]

jmortensen - I know SU's are not great for top end power, but to counter what you're saying I will myself use Norm Simpers as an example. While his SU's are not stock they are modified in ways that any person could easily do themselves. In his case it is definately a case of good head work, together with the diesel crank, that really gets his car moving. I find it very hard to believe that switching to tripples over SU's would have in itself have netted me 30 extra hp at the wheels. Yes it would moved the powerband up higher and would have resulted in a higher hp peak, but 30hp??? I'm thinking more like 10-15 at the most. Whereas I know two guys personally that dynoed and got around 30-40ish hp from having some good head work done (I think the guy that got 40 more also went with a different cam when he had his head done but I dont remember for sure). But both headwork and triples serve basically the same end, which is getting better flow into and out of that head, so yeah they both will benefit quite a bit. But at what cost? I've seen triples go anywhere from $500 for a used set to $1500 for new ones.

OK, but I wasn't arguing that they were cheap, or that they were easy to tune, but I still gotta take issue with 40 whp increase to the wheels from port work and 15 whp from Mikunis.

 

Someone else with triples back me up here. I'm thinking more the other way around. Your standard port job probably nets 15 hp on a good day, while switching to Mikunis from stock SU's is EASILY worth 30 whp, properly tuned. I think it was probably worth MORE than 30 on my car and maybe that was partially due to the already ported head that I couldn't make use of with the SU's, but I have no way to prove the #'s.

 

Dan, do you have dyno figures from the SU days you can use to back me up? If not numbers, a gut instinct? Anyone else?

 

Jon

[Guest bastaad525]

ah I should mention one thing that you hinted at, triples and head work do play off of each other in a way SU's cannot. Case in point, my friend with the 40hp increase from the head work was already running tripples. I am sure that the increased flow potential of the head was very well taken advantage of by the much better flowing triples, no doubt. I also wouldn't call what he had done simple 'port work' he also went with larger valves (from a chevy I believe)... I dont know what else but I know he really went to town on that head (which by the way was a P90 so he also did have it shaved and shimmed. This was a few years back so I may be off on something or missing something. I also seem to remember he spent somewhere in the range of $2500 on that head. I'm definately not trying to say that a simple port and polish job would net you 40hp But I know I've heard more than a few instances of 20-30 gained from just that, regardless of which carbs were being run. Honestly never once heard anyone claim more than 15hp from just switching from SU's to trips even after a good dyno tune, but seeing as you are going from two small openings to six larger ones, I guess I really can't say 'it's not possible'. Either mod is going to net you more power for sure.

[johnc]

johnc - hell I think even a stock 135hp L28 would feel pretty quick with 4.63 gearing!!! What gear would you consider to be 'street gearing' for your motor though?

 

I didn't mean to imply "street" anything with my engine and car. The fact that it doesn't have a flywheel and only a 5.5" diameter clutch makes launching the thing a nightmare. I can't even drive it onto my trailer. There's really nothing "street" about my car and I would rather walk to the store then drive it through 5 blocks of traffic.

 

I appreciate the compliments, but Jim Thompson built my engine, not me - I can't take any credit. I'm a suspension guy so take what I say about engines with that in mind. To me, engines get in the way of good suspension design.

 

How much do I have in my car? Well, if you earned the California minimum wage you would have to work 1,018 eight hour days to pay for it.

[Mikelly]

Well, As John has reminded me several times, I've been out of the Lseries motor for quite a while!

 

I also agree with the comments about understated tuning of the carbs and overstating cam and head work. I experienced just that with large valves and big cam properly shimmed in an L28 setup. If you can't get the induction sorted out, you will NOT be able to take advantage of the induction, porting, and larger ingestion of the system... SUs are a JOKE on Lseries motors that have modified heads. They simply can't flow enough CFMs...

 

Mike