smorganjr

Im building a Jimmy Smith Motorsports rock bouncer chassis with a lq4 motor. The rig is 4x4 with one ton axles, 4.56-4.88 gear, th350 trans and atlas style transfer case with 43'' super swamper tires. Its going to weigh somewhere in the 3500# range. It will not see very much crawling speeds, it will be a hill climbing machine! These rigs are built for 90% of the time in use they are at WOT! My big question is what heads do you guys think will work the best for my application? i'm looking for somewhere between 5-550hp, as always the more the merrier! What do you think will need to be done to reach this goal?

PREDATOR-Z

Tfs....

smorganjr

im sorry, tfs...??

redtan

iTrader: (5)

Go with the 243s...you will need the higher compression that those offer more so than the top end power that L92s offer.

TFS are trick flows, but unless you have a budget of 2500 for heads you should go with the original plan of 243s.

Always2Slow

iTrader: (8)

243 heads are a good option but I would still say to do the l92 heads. Your going to need air flow to make power. Compression doesn't add as much power as the amount of flow does. You have a much better designed stock intake to use that doesnt cost 1000s of dollars. Another good option is to get a set of stock ls2 pistons in your lq4 so you can raise your compression up.

redtan

iTrader: (5)

I guess I missread your post, if you plan on going WOT 90% of the time that's probably going to mean high RPMs where the L92s shine over the others. So go with those.

snowman47

I love these rock bouncers! BA machines haha. What other upgraded components will be in this lq4?

Storm Trooper

iTrader: (11)

Have the l92 heads milled. They flow much better...

96capricemgr

iTrader: (1)

Far as the intake manifold argument the stock truck intake is decent if staying cathedral port. It is the true LS1 intake and worse yet LS4(FWD Impala) intake that are not so great.

The 317s have the same ports as 243s.

Take a closer look at what you have and consider massaging it to work. 500fwhp is not anything exotic these days. I think some porting on the 317s and a good cam can get you there. I believe it cost $200 extra to have the 317 chambers welded up so they can be CNC'd to 243 size, probably can't find a pair of 243 cores for that.

PREDATOR-Z

Personally I would stick with cathedral due to the fact that they are less sensitive to cam choice (Like more versatile, L92/LS3 are more specific).
Plus from my experience, keep the valve-train as light as $$ possible to sustain high rpm without control issues.
I would look at a solid roller setup with heads to match (also modded to accept thick push-rods).

smorganjr

Thanks for the input guys, i have been thnking about doing the FAST 92mm intake and TB. Dont want to break the bank on this engine but also not afraid of paying for quality parts if thats going to be ther better route.

garygnu

listen to Pred-Z ,unless you do a custom cam for $425 .you mite get ls3 heads form SDPC for $650.you will need the matching intake for those ports.what will be the bore of your short block ?the l92/ls3 heads work best with bigger bores .if the valve is too close the cylinder wall you will hurt port flow and power.

smorganjr

Forgot to mention i wont be able to use the stock intake because of clearence issues with the engine cover. thats why i was thinking the FAST intake and tb would be best since im goig to have to spend money on a intake anyway.

smorganjr

Thanks man, they are definately alot of fun! Nothing special in the bottom end other than rod bolts and the already mentioned parts.

smorganjr

I was planning on having a custom cam, just figured that would be better than any off the shelf cam for what im doing. i spoke with cam motion about doing a cam already just need to figure the rest of the equation out before i can proceed. Do you reccomend a specific cam company to have the cam made? The short block is stock bore, if i have problems on down the road with the bottom end it will probably get stroked. But never know if that will ever happen.

KingPin1094

iTrader: (12)

Cathedral will keep alot of the power and torque lower because of the higher velocity of the air charge, whereas the l92 heads with a larger intake runner have slower velocity bringing the power and torque up higher. So it depends on what you think youll see more of, low or high rpms.

lemons12

iTrader: (71)

Negative.. Stock l92 setups peter out very quickly.
Most are done by 6k rpms and allow you to shift around 6200 max.

For high rpms, l92... For mid range, cathedral.

Btw.. an ls3 won't clear and a fast Will? Doubtful...

KingPin1094

iTrader: (12)

Isnt that exactly what i said? l92 is better at higher rpms, and cathedral is better down lower? My l92 setup doesnt really start making torque till 3,000-3,500 and carries till about 6,200 with a stock ls3 intake.

squirlNUTZ

If you will buy quality parts then I'd say contact Brian tooley, get a set of trick flow specialty 220 as cast and have him spec you a camshaft for what you have. He has all the parts you will need to make a solid performer out of your lq4 stock bottom end. After you are done mailing heads around the country( providing you do not have a builder close by) you will be money ahead. You can also get a fast from him and while its there he can port match it to the TFS heads. Talk with him. He will answer all your questions and it will be a one stop shop to reliable power.
There are many other choices as well, but I doubt any one will deny Brian will hook you up

bozzhawg

Something else is wrong with your combo, no way should a 408 be putting down those low numbers.

Most of the guys I see saying L92's or LS3's suck down low have other issues with their combos.

Martin at Tick use to be the same way until he actually started using them. Before, he had never fooled with them and would trash them and regurgitate the same bull posted by the close minded, but once he actually started using them, his opinion changed. I think he has some LSA's for his car now.

You can make power with them and it will not be all top end power either.

I have used both cath and square. Which one do I like better? Depends on what I am trying to accomplish and how much money I want to blow. I will say for the money, LS3's are tough to beat.