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Hey there fellas, buying parts for a LQ4 Rebuild and have questions about the Cam Selection, In my summit racing basket i have a LS Pro rotating assembly with a 12cc dish, and TFS GenX 225 heads with a .51 MLS Headgasket, i believe that puts my engine around 9.5:1 CR, I was eyeballing a Sloppy Stage 2 by Trickflow (https://www.summitracing.com/parts/tfs-30602003) but i noticed it said "Compression ratio of 10.5:1 minimum" I never knew there were minimum Compression ratios for cams... I live in canada where we have no E85, only 91 (94 if your lucky) pump gas (was going to add water/meth injection for mid/high boost). Should i change the rotating assembly over from a 12cc dish to a flat top? would put me at 10.6:1ish for CR... would that be ok for a Pump Gas Turbo build? Should i get a different Camshaft? I remember reading that a lower CR is better for boosted applications but i don't know if that holds true still. Any suggestions for 91 octane pump gas engine?
A more radical cam reduces the dynamic compression. This is why engines with very wild cams have very high compression ratios.
The Sloppy Stage 2 cam is fairly lumpy for a street cam. If running 91 octane,you can easily use the 10.6:1 compression.
Before i pull the trigger on this engine build, can anyone spot anything i left out? Gaskets? or if there any specialty tools a newbie should have? I am alittle curious about the LS9 headgasket being a bore of 4.10 vs the LQ4's 4.0 bore. But everyone says get a LS9 MLS Head gasket... (Gen 3 LQ4)
Have you researched Harland Sharp's reputation with LS roller rockers?
I think you can find a much superior LS roller rocker for fairly similar cost.
I have not, thank you for the advice ill look into it.
I am actually a little concerned about Piston to Valve clearance now... Stock LQ4 is a 75cc Chamber with a 9.4 compression ratio, so if i go with flat top pistons with the 65cc TFS 225 heads for a 10.6 CR, will that mean i have to pick a smaller cam?
I’d go for the higher compression ratio. Select the head gaskets to get your quench correct.
maybe look into using all the real estate available for your block. Stroker engines are great. get a cam spec’d for your build.
I’d go for the higher compression ratio. Select the head gaskets to get your quench correct.
maybe look into using all the real estate available for your block. Stroker engines are great. get a cam spec’d for your build.
I feel stupid saying this, because it is stupid... but i am hoping for better fuel economy and durability with the smaller displacement lol.
I feel stupid saying this, because it is stupid... but i am hoping for better fuel economy and durability with the smaller displacement lol.
Compression adds economy. The tighter you can squeeze a gallon of gas, the farther the vehicle will travel on it. This is why modern OEM’s are upping compression on their stuff. Also, and a big one here, but tuning is everything. It’s more important than anything in your basket. Bad tune and you’ll hate the thing and sell it. Average tune and you’ll feel underwhelmed and always wonder what happened…I should have made a lot more power..type of attitude. Get a great tune, and you’ll see what I’m talking about. Tuning is everything. You can tune for mileage as well. My heavy Chevelle with a 750ish hp 434 gets over 20 mpg. It’s all about the tune.
So having said that, I agree with Jason above…go with a stroker setup, for very little more cost and a lot more power (torque) potential. There’s a few items in the cart you won’t really need at that point, which could save you even more.
Compression adds economy. The tighter you can squeeze a gallon of gas, the farther the vehicle will travel on it. This is why modern OEM’s are upping compression on their stuff. Also, and a big one here, but tuning is everything. It’s more important than anything in your basket. Bad tune and you’ll hate the thing and sell it. Average tune and you’ll feel underwhelmed and always wonder what happened…I should have made a lot more power..type of attitude. Get a great tune, and you’ll see what I’m talking about. Tuning is everything. You can tune for mileage as well. My heavy Chevelle with a 750ish hp 434 gets over 20 mpg. It’s all about the tune.
So having said that, I agree with Jason above…go with a stroker setup, for very little more cost and a lot more power (torque) potential. There’s a few items in the cart you won’t really need at that point, which could save you even more.
I should say that i have a new S476 Turbo that is going in the vehicle as well, is a stroker setup ideal for a turbo vehicle?
I should say that i have a new S476 Turbo that is going in the vehicle as well, is a stroker setup ideal for a turbo vehicle?
Ideal? Sure. Necessary? No. Rule of thumb is that if it runs good in NA form, it will run better in FI form. Of course going with FI, you won’t won’t to bump compression to the moon. Keep it at 9.5-10ish. Also pay attention to piston design and ring placement on the piston. A stroker setup will often push the rings upward because the pin location is raised. Rings closer to the dome in a big-boost setup are going to run much hotter, so you must plan for that. If your going to boost it for sure, maybe the package you have in the cart is worth keepin after all.
I am actually a little concerned about Piston to Valve clearance now... Stock LQ4 is a 75cc Chamber with a 9.4 compression ratio, so if i go with flat top pistons with the 65cc TFS 225 heads for a 10.6 CR, will that mean i have to pick a smaller cam?
With Forced Induction planned, I'd rather have closer to 9.4 CR than 10.6 CR. Best bet is to decide have a cam guru spec the cam to your engine build. The Sloppy S2 228/230 is a good cam but there are better cam choices properly matched to your build. Summit is very good at helping with cam selection and since your ordering from them, I'd discuss cam choice with Summit. Their Ghost Cam (222/233) is very popular for NA and forced induction build plus several others.
Has the LQ4 iron block been inspected to make sure it doesn't need to go .005 or .010 over?
FWIW - Have a set of needle bearing stock LS1 rockers w/263,000 miles and no issues. Ran another set of stock rockers 130,000+ miles with a 224/224 .581/.581 lift XER cam. Have stock style w/retained needle bearings on my 416 as well. Jesel rollers were a real fiddly hassle to set up on my 383 LS1.
Regarding strokers, I have three and a 4th planned. I love them With that said if long durability and high mileage is critical I'd consider that a stock stroke LS can go 300,000+ miles etc.
Even well build and well cared for 4 inch stroke strokers with correct piston taper etc are probably going to want a refresh by ~60,000 miles. Occassionally, one will go 100,000+ miles but that's rare, am aware of one dojng that. Badly build strokers with wrong piston taper will have issues in less 10,000 miles guzzling oil etc.
Usually high mileage durability isn't a concern but just wanted to share info etc.
Get a felpro gasket kit. Save money. Reuse timing set. Get an upgraded timing chain. Find oem valve covers used. Ls9 gaskets should be fine. I would use felpro MLS gaskets in the kit. Trickflow heads will be lucky to get to your door by the second quarter next year, I would order texas speed as casts with upgraded valves and tsp or ws6store oem rockers. Big bore chamber option on heads.
You could get a crate engine from GM Performance cheaper than your cart total. Several to choose from. A turn key LS3 is even cheaper.
I am sure you have your reasons, just wanted to mention it.
With Forced Induction planned, I'd rather have closer to 9.4 CR than 10.6 CR. Best bet is to decide have a cam guru spec the cam to your engine build. The Sloppy S2 228/230 is a good cam but there are better cam choices properly matched to your build. Summit is very good at helping with cam selection and since your ordering from them, I'd discuss cam choice with Summit. Their Ghost Cam (222/233) is very popular for NA and forced induction build plus several others.
Has the LQ4 iron block been inspected to make sure it doesn't need to go .005 or .010 over?
FWIW - Have a set of needle bearing stock LS1 rockers w/263,000 miles and no issues. Ran another set of stock rockers 130,000+ miles with a 224/224 .581/.581 lift XER cam. Have stock style w/retained needle bearings on my 416 as well. Jesel rollers were a real fiddly hassle to set up on my 383 LS1.
Regarding strokers, I have three and a 4th planned. I love them With that said if long durability and high mileage is critical I'd consider that a stock stroke LS can go 300,000+ miles etc.
Even well build and well cared for 4 inch stroke strokers with correct piston taper etc are probably going to want a refresh by ~60,000 miles. Occassionally, one will go 100,000+ miles but that's rare, am aware of one dojng that. Badly build strokers with wrong piston taper will have issues in less 10,000 miles guzzling oil etc.
Usually high mileage durability isn't a concern but just wanted to share info etc.
Thank you, exactly the information i was looking for. Thing is, i want dead nuts reliability with a turbo, i'd like to run 91 octane on the street and keep it on wastegate (7-8psi) for the street/daily driving, but i also want the ability to turn on a boost controller for 14-16psi and have a water/meth injection kit come on for added octane/charge cooling (also, that sweet steam cleaning effect). I only see two CR options for the Summit LS Pro Rotating assemblies. 9.6 and 10.7 but while i was trying to figure out the head gasket thickness they would of used to come up with those ratios (so i could see what my .055 headgasket would result in for a final compression ratio) i found out that the rotating assembly would have to be balanced with the stock crank, which means i should just buy a full Summit rotating assembly that includes bearings etc.[Edit] I found out the full rotating assembly from summit is not balanced, looking on Texas Speeds website it seems i can order a balanced .030 over rotating assembly from them with a better CR of 9.7 with my chosen headgasket for the same price[/edit] I also have not had the block inspected, however.. This makes me think... What if i keep the stroke stock, But have it bored .030 over? is there enough wall thickness for it? apparently that creates more power but higher up in the RPM, being stock stroke that would mean it would be reliable? a 370 seems like a neat number for displacement to me. Also the TFS heads require a roller rocker apparently and looking at steel roller rockers the added tip weight would increase the likely hood of valvefloat, the max lift of the factory TFS Heads/springs is .600 which means with a 1.72 ratio on a .585 lift cam i would be sitting right at .592 lift. With the additional weight on the tips of the valve i feel like i should step down to a smaller cam anyways. alternatively i guess i could buy the Bare TFS Heads, valves and my own springs to compensate for the additional weight.
Bspeck82
Get a felpro gasket kit. Save money. Reuse timing set. Get an upgraded timing chain. Find oem valve covers used. Ls9 gaskets should be fine. I would use felpro MLS gaskets in the kit. Trickflow heads will be lucky to get to your door by the second quarter next year, I would order texas speed as casts with upgraded valves and tsp or ws6store oem rockers. Big bore chamber option on heads.
I kind of want to jazz up the valve covers, plus since i don't know how big the aftermarket roller rockers are, better to be safe to get the tall valve covers. As for the lead times, wouldn't be an issue. I am parting it together, ordering it and building probably march next year.
Bspeck82
I would also see if frankenstein has some ported heads laying around and maybe an ultra low ram or BTR equalizer Intake for the boost.
I have a performance world intake on my LM7 right now, going to reuse it.
Jake Wade
You could get a crate engine from GM Performance cheaper than your cart total. Several to choose from. A turn key LS3 is even cheaper.
I am sure you have your reasons, just wanted to mention it.
Reason i am going with a LQ4 over a LS3 is i have a Gen 3 24x/EV6 LM7 that has a Terminator X Max on it, i wanted to be able to swap the engine over without having to buy a new terminator kit and i want to address all the weak points while i build, plus a turnkey LS3 is 430hp at the crank, would much prefer 430 wheel without boost.
@Gumby83 as mentioned by another member, a new GM crate LS3 maybe worth considering. The LS3 is a cam swap & valve springs away from ~550 flywheel ~475 whp. Even ~500whp is within reach with a rod mod'd LS3 intake and a few other tweaks. Chevrolet Performance LS3 430 HP Long Block Crate Engines 19432422.
Also available with intake, fuel rail, injectors, coil packs, water pump, TB etc.
Compression is 10.7 and folks boost stock compression LS3's on a regular basis. However, all my set ups are NA. Hopefully the boost commentary will be from the folks that have experience boosted LS set ups.
Of course a lot depends on desired power goals and intended use etc.
Last edited by 99 Black Bird T/A; 09-10-2022 at 07:24 AM.
So spend more on a slower engine? Backwards way of thinking. Op can rebuild this engine for much less than his shipping cart reflects. He is just spending money on things he doesn't need and overpriced parts.
Listen. Get a full rebuild kit on ws6store. Max effort ws6store rocker arms. Ditch the tfs heads. Port the stockers. Tfs is wayyyy overpriced for that as cast junk. Summit ghost cam. You don't need a cam degree tool. Engine is out, put it at TDC and line dot to dot. Ditch the timing set and just get a new ls2 chain. Paint oem valve covers, aftermarket stuff always leaks. Timing cover alignment tool? Lol who needs that? BTR gaskets are overpriced. Felpros will do. I probably just cut the cart in half and now you have money to spend on things that actually help.
Before you order any rotating assembly please have your block checked first. I’m sure you will need a .005 cleanup and then you need to order the right size piston for the clean up job or if you plan on punching it out .020-.030. Figure this out first. If you are not stroking maybe just look into rods and pistons. Guys boost the hell out of stock cranks if you plan on keeping close to stock cubes.
09-08-2022, 04:43 PM
Compression Ratio and what camshaft? 
With that said if long durability and high mileage is critical I'd consider that a stock stroke LS can go 300,000+ miles etc. 
