Road Race Enduro L28 Engine Build

[z-ya]

This is a build thread, so maybe the admins want to move it to the members project area.

 

The main goal of the build is a super reliable road race L28 engine. I want this engine to last for years, so it is not being built for all out max power. The other goal is to use as many of the Bob Sharp engine parts that I have acquired recently.

 

Basic engine specs:

 

- Max RPM: ~7000

- Max CR: ~13:1

- Bore/Stroke: Stock stroke/0.020-0.040 over bore

- HP goal: 250WHP

 

Some of the Bob Sharp parts I'll be using:

 

The is sorta what it will look like:

 

 

I have these headers, collectors and twice pipes.

 

Carbs:

 

 

Probably the middle damper:

 

 

Valve cover:

 

E31 head:

 

And a bunch of other stuff including a remote pickup oil system including competition pan and oil pump cover.

 

I plan on making this build thread as detailed as time will allow (got to get it built by next spring).

 

Stay tuned.

 

Pete

[johnc]

It will tough keeping to your 7,000 rpm redline and making your 250whp goal. You'll need a lot of cam to take advantage of that 13 to 1 CR and then you'll need rpm to make that cam work. 8,000 rpm might be more realistic. Good luck with the build.

[z-ya]

It will tough keeping to your 7,000 rpm redline and making your 250whp goal. You'll need a lot of cam to take advantage of that 13 to 1 CR and then you'll need rpm to make that cam work. 8,000 rpm might be more realistic. Good luck with the build.

 

Thanks John.

 

CR will be somewhere between 12 and 13:1. I'm looking for reliability first, so I'm going to start at 7000RPM redline. I'll do my best to build it to support 8000RPM, but I may never run it there.

[BRAAP]

This will be a sweetheart build, nice collection of go-fast bits.

[josh817]

Are those dampers or pulleys? If they're dampers, they look pretty old. How is the rubber inertia ring? I'm curious if it has held up over the years or if the outside has spun.

[z-ya]

Are those dampers or pulleys? If they're dampers, they look pretty old. How is the rubber inertia ring? I'm curious if it has held up over the years or if the outside has spun.

 

Hi Josh,

 

They are old, and they are dampers. And yes, they have rubber rings. I haven't given either of them a good inspection yet.

 

I don't want to turn this thread into a damper discussion, so let's keep the discussions focused on the build as a whole.

 

Thanks,

 

Pete

[JMortensen]

I'm a bit stumped as to why John would see this as an issue.

 

Mark is making 85hp/liter with a 3.1 and lower compression and redline with smallish 40mm carbs:

http://forums.hybridz.org/index.php/topic/24798-na-31lhead-camshaft-questions-no-shortcuts-max/page__view__findpost__p__678488

 

Then there was that other guy, John Coffey, who got 320bhp 287whp at 6800 with a similar compression ratio on 3L. That's 95 hp/liter, or 267 for a 2.8:

http://forums.hybridz.org/index.php/topic/42632-highest-numbers-for-na-stroker/page__view__findpost__p__353597

[johnc]

I'm a bit stumped as to why John would see this as an issue.

 

Mark is making 85hp/liter with a 3.1 and lower compression and redline with smallish 40mm carbs:

http://forums.hybridz.org/index.php/topic/24798-na-31lhead-camshaft-questions-no-shortcuts-max/page__view__findpost__p__678488

 

Then there was that other guy, John Coffey, who got 320bhp 287whp at 6800 with a similar compression ratio on 3L. That's 95 hp/liter, or 267 for a 2.8:

http://forums.hybridz.org/index.php/topic/42632-highest-numbers-for-na-stroker/page__view__findpost__p__353597

 

I guess I need to 'splain myself and I could be mistaken in assuming the 7K number Pete posted was a redline.

 

If your redline is 7K and you make max horsepower at 6.8K then you'll need an awfully close ratio transmission to keep the engine in the power band on a race track. Some additional rpm headroom above the horsepower peak is a good idea.

 

I didn't word my post above very well.

[JMortensen]

Suggestion: if you want to follow the "ride the crest theory" use Mark's cam. His hp peaks at 6000. Or just get a cam that makes so much more power that it is better than a cam with a lower hp peak that you can ride the crest on. That was a new idea to me until a thread about LSx cams. Apparently guys autoxing are finding the bottom end unreliable over about 6500, but some of the options make so much more power that even though the cam might peak over the redline you want, you'll still get more power out of it from say 4000 - 6250 than if you go with a smaller cam.

 

http://forums.hybridz.org/index.php/topic/80120-cammed-ls1-guys-need-advice/page__view__findpost__p__761479

[josh817]

Sorry Pete, I promise I won't rob your thread. I'm eager to see how this works out for you.

 

 

I too was curious about the horsepower thing but didn't want to speak up.

 

Goodluck Pete. I wish the best and hope you don't end up with another "bad day at the track" box.

Edited November 25, 2010 by josh817

[z-ya]

I was thinking about using the Isky Z-196 cam:

 

http://www.iskycams.com/pdfcatalog/2004-05/page176.pdf

[Tony D]

First thing I thought of was 'why the low rpm limit'---short of using CAST pistons, there is no way I'd limit an L-Engine for endurance racing to that low an RPM range. 7500 would be a 'streetable' engine, and at least 8K for a track engine.

 

That is WELL within the 'longevity' range of an L-Gata. Though the romance of antiquated balancers may prove your undoing...I'd skip the vintage stuff and put it on a shelf for lookin' at, and put a properly designed modern damper unit on the engine for the best results.

 

"Vintage" and "Longevity" are usually mutually exclusive. Just my thoughts.

 

And don't get stuck on catalogged grinds. Call and talk to Ron and give him your engine details. They will custom tailor the lobe centers, split the duration and grinds, all sorts of things to come up with a cam specifically for YOUR engine. It won't cost any more or any less than buying one out of the catalog, and you can send in a good 'JAPAN' core for the grind, getting better compatibility than the CWC core used for their stocking grinds.

[z-ya]

First thing I thought of was 'why the low rpm limit'---short of using CAST pistons, there is no way I'd limit an L-Engine for endurance racing to that low an RPM range. 7500 would be a 'streetable' engine, and at least 8K for a track engine.

 

That is WELL within the 'longevity' range of an L-Gata. Though the romance of antiquated balancers may prove your undoing...I'd skip the vintage stuff and put it on a shelf for lookin' at, and put a properly designed modern damper unit on the engine for the best results.

 

"Vintage" and "Longevity" are usually mutually exclusive. Just my thoughts.

 

And don't get stuck on catalogged grinds. Call and talk to Ron and give him your engine details. They will custom tailor the lobe centers, split the duration and grinds, all sorts of things to come up with a cam specifically for YOUR engine. It won't cost any more or any less than buying one out of the catalog, and you can send in a good 'JAPAN' core for the grind, getting better compatibility than the CWC core used for their stocking grinds.

 

Hey Tony,

 

My concern is ignition stability over that RPM and CR. From what I've read, anything over 7000RPM for a significant periods of time requires a crank trigger. L series distributors are not stable much over 7000RPM. I've got the crank trigger setup (see left most damper), but the two vintage organizations I want to run with require triggering from distributor. It basically has to be C production legal (or I'll be running with GTU cars).

 

Again, I will do the things I've learned hear and by reading the books that are out there to build it to support 8000RPM. I'm not hung up on the vintage damper at this point. I may run a modern one, or one of these. I think it will come down to budget. So if I have to limit RPM, that is what I'll do.

 

As far as the cam I've talked to a couple people an they suggested this grind. It's the same as the old Datsun competition cam. It's got decent midrange torque (which is good for some of the short tracks I run), and is much easier on the valvetrain than 590+ lift grinds. Anyway, I'm still open to suggestions.

 

Thanks,

 

Pete

[johnc]

Hey Tony,

 

My concern is ignition stability over that RPM and CR. From what I've read, anything over 7000RPM for a significant periods of time requires a crank trigger. L series distributors are not stable much over 7000RPM.

 

First I've heard of that for any use under 8,000 rpm. I ran a ZX distributor on my engine without any problems with an optical trigger. New bronze and steel gears are probably a good idea and go through the distributor to make sure the bearings and bushings are all good. I did have an issue where the oil pump drive snapped a tang but that was very specific to my engine (I also broke alternator mounts). Adding a .0016" bronze shim in between the distributor and oil pump drive tangs solved that problem.

[josh817]

Pete, do your clubs allow for showing proof whether they ran that sort of stuff back then, maybe? I know CVAR down here says if I can provide documentation or a photo of a certain setup, then I can run it.

[z-ya]

Pete, do your clubs allow for showing proof whether they ran that sort of stuff back then, maybe? I know CVAR down here says if I can provide documentation or a photo of a certain setup, then I can run it.

 

They did run crank triggers back then, but in the GTU class.

 

This is a C production car:

 

 

This is GTU:

 

 

I'd get my butt handed to me in the GTU class.

[280zNHChris]

Those GTU rims are nice, look like the ones I have all blasted at my shop, how did the valve cover not make it up? Picka color, any color.

[z-ya]

Those GTU rims are nice, look like the ones I have all blasted at my shop, how did the valve cover not make it up? Picka color, any color.

 

Chris,

 

The entire car is freakin' beautiful. Rims, everything.

 

We got plenty more coming up for powder coat.

[z-ya]

More photos:

 

Headers:

 

 

Modified Nismo oil pan for external pickup:

 

 

Nismo oil pump cover:

 

 

Modified timing cover with crank trigger:

 

 

Water passage blocked (any ideas why?):

 

 

Nismo sprocket:

 

 

Thermostat housing. Not sure where te -3AN lines would go. Ideas?

 

[Tony D]

We triggered the bonny engine from the distributor quill, using the small e-motive wheel.

 

As for the blocked water passage, there has been one guy here (ahem) talking about removing the internal bypasses back to the inlet of the water pump to maximize cooling flow through the block for some time now and (sniff sniff) he's feeling a bit put out that nobody has listened and immediately recognized another "lost performance cooling modification" for the L-Gata! That goes for the -3 AN lines as well. Take a look at the discussions on the #5 Cooling Thread and all will be alluded to, if not outright explained...

 

Some people plug the return in the block with a flushseal plug, but putting aluminum in there does the same thing.

Edited December 1, 2010 by Tony D