advice needed

[Guest ZagatoZ]

hi guys, first post for me though ive been lurking awhile.

ive got a 74e 260 thats basically stock except for triple 44PHH's with a short runner mikuni manifold. id like to drop a 280 motor in with either the e88 currently on it or a worked e31 and keep the carbs. id really like to shoot for 250hp at the crank. is this even a reasonable goal without getting into the internals? id like to keep the compression streetable and keep things fairly simple for this build.

here are my carbs jettings:

Main airjet=200

Main jet=150

pilot jet=57.5

large venturi=34

starter jet=160

also, butterflies have a 175 stamped on them if thats important

 

recommendations on jetting would be great!

Thanks for any help

[Guest bastaad525]

Without a cam and headwork I'd say no on 250hp at the crank. The tripples are a good start but really, and I hate to say this as I don't want to offend, but they are wasted on a motor that doesn't have the right cam and head work to take advantage of them.

 

As a matter of fact many people here do agree that tripples on a stock or mostly stock motor can actually HURT performance vs. SU's or EFI.

 

But that's neither here nor there since that's what youre running right now. So back to your original question, no I really doubt you could hit 250 crank hp without some internal motor work.

 

For comparison, I built up a very healthy N/A motor, overbored to make it 2.9L (on a F54 280 block), minor head work on an N42 head, 10.3:1 compression, mild cam, rebuilt SU carbs, headers and full exhaust, and 'only' made about 200 crank hp. With much more headwork and tripples I probably could have bumped it up 20-40 hp.

[briann510]

or you can do a 3.2 stroker and make 320+ crank HP like we have. we did 278 RWHP and still doing some tuning. we just ordered our fogger nitrous kit and will be throwing another 150 HP at it.

 

FUN!

[Tony D]

Well, we had 315 to the wheels on a .040 L28...

 

We didn't need on stinkin' stroker...

 

Heck, 286 was the baseline for us after going TWM Induction 45's...

[SHO-Z]

I am in the middle of a supercharged forced induction on tripple SK Racing 45mm carbs headers with 2-1/2" exhaust. From the research that I have done with 10 PSI of boost I should get around 250 hp at the crank on a stock L28. I am using a eaton M60 supercharger with intercooler. The carbs are still sitting on the shelf next to the supercharger, so I have a ways to go on the project.

 

If I blow it up I guess I will have a "V8" instead!

[briann510]

good numbers Tony, but id love to get a rundown on EXACTLY what was done to the engine to make that HP. race gas only? horrible idle with a .550+ lift cam?

 

all it takes in money to make whatever HP one wants to make with any setup used. stock block, stroker, turbo etc...different "strokes" for different folks..LOL

[Guest ZagatoZ]

thanks for the help. money is the main problem of course so unless the machine work is cheap for a stroker i dont think ill be going that way for now. mr D i would appreciate it if you could elaborate on the setup you used to make those kind of #s. if i can run that on pump gas that will definitely be the way i go.

 

what i have planned for an NA setup:

280 block

flat tops

fully worked ported polished yada yada n42? seems to be the favorite

header, exhaust

3x 44 phh on a short runner mik man.

lumpy cam, but nothing i cant live with everyday. low end grunt isnt TOO important but i dont want something i have to rev to 3gs just to get going.

280zx ign.

5 speed, not sure which would be best

3.7 with CVs out of my junked 300zx

i could always go turbo, for the same or less money but i like the idea of all motor. plus turbo motors are hard to come by in MN.

brian, your stroker is exactly what id like to build someday but unfortunately the budget doesnt allow it right now.

 

on another note, i tore down my carbs to rebuild and just learn how the internals work and id like to know if my jets are ideal for a 2.6. it ran really rough when i got it and the front carb was leaking gas out a hole to the left of the carb throat. a family friend who is a mechanic tried tuning them up but didnt do a very good job but he DID say this was probably too much carb for this motor. can 44s be jetted down enough to be happy on a 2.6?

[briann510]

you can build a stroker that doesnt cost near as much as ours did. ous did because of who we used to do it and that he offers a lifetime warranty on it. couldnt resist that warranty.

 

we could have gone turbo for ALOT cheaper and made more HP as money want an issue on our z engine, but turbos dont get me off one little bit and i dont like fuel injection either for looks or performance even tho its easier to tune. i like making HP on the engine with carbs and run it on pump gas. we did just order a nitrous fogger setup to throw another 150-175 HP into it so that should be fun and get us into the 10's.

 

you can bet Tonyd knows his stuff in pretty much anything z related, but he hates strokers and carbs! LOL

[Guest ZagatoZ]

im with you brian. im pretty old school when it comes to cars and id like to keep it carb'd. the simpler and more mechanical the better.

 

when you say cheaper stroker, what are we talking about here? i know the crank rods and pistons can be had fairly cheap, so what kind of $ are we talking about for machine work. i was under the impression that there is quite a bit that needs to be done and a novice cant do it. if its under a G i just might have to reconsider.

[JMortensen]

I've never had my car on a dyno, but I had a L28 with dished pistons and an E31 head (so 8.3:1 compression) with 280 valves very mild headwork, a medium sized .490/280 cam and 44s. I ran it with a Gtech and a badly slipping clutch and the Gtech showed 15.5 at 108 mph. 15.5 is crappy no matter how you slice it, but 108 in the quarter with the car, me and a passenger at 2650 lbs equates to ~261 hp according to the calculators. Then you figure that the original Gtechs read a couple mph fast because at the track they average the last 60 ft or whatever and knock the mph to 105. Hp is now ~240. That's what I was getting out of a basically stock engine (compression and valve size) with a medium cam and some very light port work.

 

Then the harmonic balancer came apart and screwed up the front of the crankshaft on that engine. I built a flat top piston engine and did a LOT more headwork. I did some prep work on the block, took all the casting flash off and put new rings and bearings in and had the whole assy balanced, but that was about it. Compression is now ~11:1 and it doesn't run on pump gas. I haven't gotten a hold of another GTech to test with, but I'm guessing it now makes another 20 or 30 hp. That is with a BONE STOCK bottom end, and a decent amount of head work. Still running the same cam, same carbs, exhaust, etc. Is this engine going to last forever? Probably not. With the amount of compression and the amount of power going on stock cast pistons, I imagine that the life expectancy of this engine will be somewhat reduced. I am thinking V8 when this one blows, which is part of why I tried to keep this build cheap.

 

My advice to maximize hp for $$$ is to go bigger than you think with the cam. A lot of guys I know went .460/260 on the cam due to the pervasive internet advice that "if you go any bigger it will be impossible to drive on the street." I believe this is the cam Bastaad used when his hot L28 put down 200 hp at the flywheel. When I bought my cam I had the advice of many people on the internet telling me what a huge mistake I was making. I remember a close friend who got me into autoxing was shaking his head and telling me how bad it was going to suck, and how that big cam would make it impossible for me to drive my car in traffic. My mistake was that I should have gone bigger on the cam. I went .490/280, and I wish now that I had gone .500/300 or somewhere in that vicinity. I drove my car to work every day for years in stop and go with 44's and a light flywheel and never had a problem with it.

 

I'd forget about the stroker. Not trying to pick on Briann, but think of it this way. The stroker is going to give you .4 liters MAX. More common is the 3.1 liter stroker. So if your new engine puts out 85 hp per liter like mine did, then you're looking at 240 hp with a 2.8, or 265 hp with a 3.1. So your extra $1500 or $2500 or whatever it's going to cost buys you 25 hp. Not the best bang for the buck IMHO. You've specifically stated that you want power cheap. If you've run out of hp with the 2.8, and it's still not what you want, then do the stroker. But there's a hell of a lot you can do for a hell of a lot less money before you go with the stroker IMHO. No replacement for displacement is true, but you gotta take into account how much displacement you're getting. In the case of 2.8 vs 3.1 stroker, you're only getting 10%. If there's something else that will give you more than 10% hp gain for less money than the stroker, that's your next move. In my experience, a big cam and some headwork and some compression will give you a lot more than 10% hp increase, and it can be as simple as putting a late 280 block with flat tops together with an early 280 head and buying a cam. There are LOTS of different ways to build the L28, and there are a lot of different arguments for different heads and different blocks, etc. Bottom line is build something with mid 10's to 1 compression and put a cam in it and run your 44's with a good free flowing exhaust and I think you'll be surprised with what you end up with. Should run on 92 octane, and be really fun to drive.

[Tony D]

Actually I will lay money we had a fraction of the $$$ outlaid for your stroker. It was built in a Garage attached to a house, and mostly from stuff ordered over the phone.

As for idle, it would idle reliably down to 400rpm which is a tick above "cranking speed" on the EFI we used.

In normal operation we set the idle to 900rpms. Had we a stock weight flywheel assembly (or even one of those heavy "lightweight" units sold for street usage) I suspect the idle would have gone lower. But having a 7" triple disc cluth that weighs 15 Pounds (clutch AND flywheel combined) doesn't lend itself to idling sowly.

 

The Weber45's we had idled around 15 to 1700 when warmed up. That was one reason to go EFI. The idle quality myths all disapear when you actually don't depend on airflow through a venturi to generate atomization and fuel mix at idle.

 

I was getting at the same thing JM is heading towards above: the stroker is really not the best bang for the buck. You would be WELL ADVISED to stick with a L28 bore and stroke, and spend money on induction and headwork. That is where the power is...the displacement you get really doesn't add that much HP at all, for all the hassle it is to get there. For all the hype, even in Japan, most guys stick in a VO7 Crank, but never go above 3 Litres because of the reliability issues from cylinder wall thickness. Like he said, cheap power will not come from boring the block and adding custom pistons.

The power in the L-Engine is, was, and always will be in the HEAD, and the induction system. You are well advised to stick with journeyman bottom end work, and standard competent preparation of the bottom end (you can do it at home, in your garage, with only a few trips to a competent machine shop), and save your money for a professional head rework of the ports, valves, etc....

 

You posted numbers, I posted numbers. Remember that the 315 number was with .080" scores in all six cylinders blowing by like crazy. We really don't know what the engine will ultimately produce until the L20A we have in the car blows up and we go BACK to the L28 for more runs on the dyno. A lot of people want to knock on our engine with the "lacks bottom end" commentary simply because of the numbers it made. Talk all you want, but when people see the torque curve from that engine on the dyno sheet, they realize quickly it is only a rearend change away from stock to get them RIGHT in the heart of the torque band for monster acceleration (for an N/A Engine, that is...) The torque curve is flat from about 3600, to well above 6000. It only moved up the scale slightly compared to a stock L28. But the top end of the graph.... it just keeps on climbing!

 

With the EFI, that 2.0 to 2.8 conversion is but a few keystrokes away, and we have that calibration right back in there, ready to hit load points on the dyno, and start tuning again...

 

No, this engine doesn't run on pump gas. But when you look at what you gain from compression, dropping back to flat top pistons and say a pump gas doable 10 or 10.5:1 ratio will not cost us appreciable power. The VW guys did that all the time: run 10:1 heads at the track, and after the run was over, swap the heads back to the 7:1 configuration for the drive home and around the commuting chores for the rest of the week.

[Tony D]

we could have gone turbo for ALOT cheaper and made more HP as money want an issue on our z engine' date=' but turbos dont get me off one little bit and [b']i dont like fuel injection either for looks [/b]or performance even tho its easier to tune. i like making HP on the engine with carbs and run it on pump gas. we did just order a nitrous fogger setup to throw another 150-175 HP into it so that should be fun and get us into the 10's.

 

you can bet Tonyd knows his stuff in pretty much anything z related, but he hates strokers and carbs! LOL

 

Well, the "looks" of this setup sure looks shabby, huh?

 

 

 

And actually, this engine is DESTROKED so the .020" cylinder bore we did will stay within the CC limit of the class!

 

I don't dislike strokers, they are just hyped to such an extent it makes me laugh.

[briann510]

i KNEW you would post those pictures to tease me!!!!

 

yes that is a nice setup but "most" dont look anything like that, not meaning i couldnt do a nice looking setup like that. like i said before if i had to do it all over again it would be a different setup indeed.

 

excellant post and info Tony. Yes a garage built engine with mail order parts can make some serious HP for sure. Like i said before i dodnt know squat about Datsun engines when we bought this car so i went the way we went just because...because of what you ask.. heck..JUST BECAUSE! lol

 

i just like the fact when the engine needs rebuilding because of normal wear or blowing it up it wont cost me a dime to have it done. that for me is well worth the extra money.

 

if i had to do it all over again would i do a stroker??? not really sure how i would do another one, but my son likes turbos so i would bet it would be some mega HP turbo engine running on race gas only pushing some outrageous boost numbers. if i had a limited budget and money was tight im sure i would have done something cheaper and not a stroker, but we said what the hell go for it.

[briann510]

jmortnesen said "So if your new engine puts out 85 hp per liter like mine did, then you're looking at 240 hp with a 2.8, or 265 hp with a 3.1. So your extra $1500 or $2500 or whatever it's going to cost buys you 25 hp"

 

ummmm try more like 60 HP MORE.

[briann510]

im with you brian. im pretty old school when it comes to cars and id like to keep it carb'd. the simpler and more mechanical the better.

 

when you say cheaper stroker' date=' what are we talking about here? i know the crank rods and pistons can be had fairly cheap, so what kind of $ are we talking about for machine work. i was under the impression that there is quite a bit that needs to be done and a novice cant do it. if its under a G i just might have to reconsider.[/quote']

 

1 FAST Z is doing a stroker in his shop right now. he would be a good source to chat with on pricing and what its costing him.

[Guest ZagatoZ]

ok, sounds to me like my best bet is to rebuild a 280 bottom end and concentrate on head work. i believe the 74 e88 was the later, less desirable head so would an n42 or even mn47 be a better choice? if i remember right the e31 comp. was too high with flat tops and 92.

oh yeah, id like to keep the compression on the edge of streetable. ive seen newer cars, mostly german running 11-12:1 on pump gas. is this not possible with the L head?

[Guest ZagatoZ]

just remembered stonehenges site has a price list for a 3.1L. cant swing that this time. cheap power is what im after

[JMortensen]

jmortnesen said "So if your new engine puts out 85 hp per liter like mine did' date=' then you're looking at 240 hp with a 2.8, or 265 hp with a 3.1. So your extra $1500 or $2500 or whatever it's going to cost buys you 25 hp"

 

ummmm try more like 60 HP MORE.[/quote']

I was talking whp not bhp. 2nd, I was comparing the 3.1 to the 2.8, which is a 10% difference. The example was correct, a 265 hp 3.1 equates to a 240 hp 2.8. If we compare YOUR 3.2 to an equivalent 2.8 then the 12.5% increase in displacement of your 3.2 will get 12.5% more hp all things equal. So if your motor makes 278 then knock 12.5% off and it makes 243.25 as an L28. So there is a 34 hp difference.

 

So it appears to me that my old engine is putting out essentially the same hp per as liter as your stroker. Probably less hp per liter than my new engine. Of course, I can't say that for sure since I never dynoed either...

[briann510]

ahhh its all good. everyone has different ideas and ways they like to do things. the only wrong way to do it is to put a v8 in it..LOL

[JMortensen]

ok' date=' sounds to me like my best bet is to rebuild a 280 bottom end and concentrate on head work. i believe the 74 e88 was the later, less desirable head so would an n42 or even mn47 be a better choice? if i remember right the e31 comp. was too high with flat tops and 92.

oh yeah, id like to keep the compression on the edge of streetable. ive seen newer cars, mostly german running 11-12:1 on pump gas. is this not possible with the L head?[/quote']

The 74 E88 is best used as a boat anchor.

 

In my experience 11:1 is really pushing it on pump gas for the L series. My car needs 95 octane and is right around 11:1 with that .490/280 cam. A bigger cam lets you run less octane, so I might be able to get away with 92 if I had the .500/300 that I want.

 

The problem with the Max N47, E88, or E31 is that they have the smaller valves. Great compression, but smaller valves. So you can swap the bigger 280 valves into it, but then you basically have to do all the same work that I had to do with my E31. Bigger seats, port the bowls to match the new big valves, get the bigger valves, etc. If you're looking for cheap there are 2 ways to go. N42 is the cheapest. Bolt it onto a flat top block and drive it away with 10.5:1. Some people with 91 octane have reported pinging, some on the East coast with 93 can run the tiny stock cam and not have any pinging at all. The other option is to get a P90 and shave it .080 and install the early 280Z valves in it. You don't need to mess with the lash pads if you do this mod and run a stock cam (probably want the bigger cam anyway though), and the compression is pretty good at 10:1. The chamber shape is superior to the N42 and N47 heads in theory. Milling the head is cheap, and if you can find a junker N42 or N47 the valves are cheap too. IMO it beats the hell out of doing all the work on an E31 or a Max N47 and I think the head design is a better one. This whole N42 or P90 thing has been beaten to death, so search if you want more info on that stuff.

 

Here's a good resource http://www.geocities.com/zgarage2001/z.html on Z heads and the P90 modification.