Steve Rea

iTrader: (1)

Hello All,

I have done a lot of searching and have found some very good information on the success people have had with the LS2 bottom and L92 top, with the medium sized cams and their goal being maximum power/torque.

However, our power goal is in the 420rwhp range, with a bulletproof engine, so I'm thinking of smaller cam and lower lift.

Application: Endurance road racing (25 Hours of Thunderhill in Dec. + multiple 3-6 hour enduros)

This year we were very competitive (qualified 2nd in Class and 4th Overall of 69 cars) yet 12 hours into the race, lost our engine, so I don't want that to happen again.

Considerations:
- low lift for reliability of valvetrain
- rpm limit of 6-6300 to promote engine longevity
- 415-430rwhp goal
- reliability is most important
- forged bottom end, new and built by someone I trust

Questions:
1) With the L92 heads, what cam would you recommend?
- SDPC has a package I've looked at of the LS2/L92 with a 212/214 that makes 500hp on their engine dyno, with a lift of something like .550

2) If I am going to be replacing springs, retainers and other items on a set of assembled L92 heads, what would a general cost be to build up the bare heads with quality (reliable for my application) parts?

I may run some sprint races, so a little extra power would be fun, however I'd want to tune it down likely for the 25 hour race.

Thanks!

Steve

briannutter

Absolutely have the block lifter bushed and have the cam bearings pinned. all bores in aluminum blocks swell with the heat and housing bores open up.


You probably know the basics:


Extreme oil cooler work and careful attention to oil line placement in relation to headers etc....wrap everything underhood.

Drysump mandatory.

maddog111

I am running that exact same combination in a road race RX7 with a GTO engine. This is an Australian soucred engine so has the front sump with L92 heads (ie the 5364 castings) and the L76 manifold. I am running GMPP controller kit. I chose the LS3 376/480 version which is tuned to run the GM Hot cam 219/228 .525. Also runs 2 qt accusump and extra quart of oil. We log oil pressure on aim dash and teh only time it tripped the alarm at 40psi out of one corner we found it had used a maybe 1/2 quart over first 100 or so laps of testing. A small top up solved this problem quickly. I am not sure if the GTO fronnt sump helps oil control as I have never run a rear sump.

Excellent driveabilty and performance. To compare around our local 2 odd mile course my old car that ran 13B turbo setup at 450rwhp lapped in 1.31 sec. The new car first day out went under 1.30 and on second test did a 1.28.9so a significant improvement with bascially a power plant change. To put this in persepctive a Porsche GT3 cup car on Michelin slicks runs 1.27's on new tyres. We are running on their second hand tyres. So a great package for about 25% of the build cost.

We plan to use this long distance but car was only finished a couple of weeks ago so have only done aboy 200 laps but not one problem yet apart from really rich tune on GMPP controller taht just saw us lower fuel pressure to get some reasonable but still rich AFRs. Will tune it soon with EFI live but havent had on Dyno yet but feels very comparable to old car at 450rwhp but just delivers it so much nicer.

RAFTRACER

Wander were you learned that.....Shouldn't you be spending time with Van today.........Merry Christmas!!!

I spoke with Steve at some length after both over our entries were done in the 25hr. event...hopefully he listened somewhat.

Steve Rea

iTrader: (1)

Haha, Merry Christmas Danny!

Yes, actually those discussions with you and Dan set the foundation and now I'm going into specifics. I thought about the equivalent to that GTO engine from Scoggin Dickey, but I think I'll go with the comfort of a forged bottom end and Dan's meticulous build. Rather not have engine be an issue again at the 25.

Turns out our data showed the oil pressure dipping to the teens on the exit of 3 and the last turn before main straight. The rpm data was screwy all weekend so I couldn't find out if there was any misshift at some point.

I really want to go dry sump and am trying to make it work in the budget.

So what is the cost to build up bare heads?

I can use those Lingenfelter ones, which could be great for sprint races and normal track/driving but I figure for endurance racing I'd have to upgrade a good amount of parts. So this makes me think it'd be practically the same cost to sell my LPE heads, and build up the bare L92's.

Danny, any idea why the Vette broke a rocker at Miller for your warm up Enduro?

Thanks

Steve

RAFTRACER

Inferior components for the application.......Aaron was using some Yella Terra components that were not robust enough for his application. We ended up putting some Comp Cams solid-roller rockershafts on it that are supposedly built by T&D machine. My car is also a solid-roller and I have been using Jesel rocker shafts for 3 years with no issues at all.

Steve build this engine once and build it right and dont skimp on any of the components or preparations. Forged pistons and crank, good rods, sleeved lifter bores with restricted orifices, good valve springs and rockershafts. If you can afford to drysump it , please do, and if not replumb your accusump as I suggested and get the check valve right near the accusump inlet to the engine .

briannutter

[QUOTE=RAFTRACER;10726832]Wander were you learned that.....Shouldn't you be spending time with Van today.........Merry Christmas!!!

That works two ways, why are you spending time reading my posts Mr. Family man?

Yes folks, if you're really bad in this life, you'll end up as one of Danny's engine components in the next.

Steve Rea

iTrader: (1)

Thanks for all the advice on reliability.

1) Anyone have experience running the LS2 / L92 package with a small cam?

2) Rough estimate of build cost of bare L92 heads?
a. If it costs a lot to build bare L92 heads with parts suitable for endurance
road racing abuse, what do AFR or other aftermarket heads come with?

Thanks,

Steve
what rockers, springs, retainers

Gen414

iTrader: (38)

If he was running Yella Terra's rocker arms on the L92 head, I do know they were a non adjustable style, and kind of a band aid until they could come out with a set of adjustable for teh L92's. Yella Terra debuted a shaft adjustable rocker setup at teh PRI showfor the L92, and should be available to us any day now. Atleast, I hope so. I am waiting on a set as I am running a solid roller with the L92's and I was not going to pay $2000 for the Jesel setup. Yella Terra's prcing should be in the $500-$600 range. No, I don't work for Yella Terra

Shawn @ VA Speed

iTrader: (3)

Hp is easy to make,your main concern should be with valvetrain dynamics,i have built several marine endurance engines over the years,no 1 problem is valvetrain,second problem is ring life,the easiest is to make hp.We use Gordon Blairs 4sthead valvetrain simulation software on engines like this to match the components properly.this also aides greatly in camshaft profiles.This ring issue is just a matter of cyl side loading,piston design,cylinder finish and roundness,and proper ring selection.All of that comes from experience and having the proper equipment to do the job.we have run several 300hr endurance tests working on ring longevity-it aint as easy as you would think.
Anyway when building an engine like this,i would highly reccommend going with somebody that had built endurance engines-there really is alot to it,you really cant just pick parts from a catalog.Remember a good race engine is an investment,a bad engine is just a waste of money.

Steve Rea

iTrader: (1)

Thanks for the input and I fully agree with you Shawn. I am very comfortable with my engine builder as he builds LS engines for off-road racing, which has to be about as brutal as it gets when it comes to endurance.

It turns out that I will be reusing the Lingenfelter heads that were on the previous engine, as they came out with only a couple bent valves. I am just getting ideas here, with the detailed specs being determined by my engine builder.

I've also decided to go dry sump, and am just needing to do some research with oil pan fitment.

Thanks again for everyone's time and experience shared.

Steve