418ci ls3 n/a supposed to be 650hp with prc 237 heads

**Gto600bob** · 01-14-2012, 05:41 AM

I am having a 418ci ls3 with 11.5 compression from Texas speed built and was wondering if anyone is using their 237cc head from precision race components? They advertise the 418 to easily accomplish 650hp with a pretty aggressive cam, but the flow numbers of their head is lower than the afr and trickflow head at the same valve lift. I want to get the most n/a power possible from this motor anyone have a head suggestion?

**mark21742** · 01-14-2012, 01:07 PM

Not really a head suggestion, but you might want to go a little higher compression.
In my 408 I went with 12.5:1 compression and a 255/263 .624/.624 115lsa cam....with this large of a cam the intake valve closes at 85 degrees abdc and drops the dynamic compression down to 8.22:1 so I have no problem running pump gas with full timing and no knock.....for every full point of compression you go up (10:1-11.0) you gain 3-4% average torque and HP across the whole rpm range.

**Gto600bob** · 01-14-2012, 03:06 PM

What was the cc of the head you chose and head gasket thickness. Or did u use ur stock ls2 head?

**mark21742** · 01-14-2012, 04:24 PM

Ported and milled 241's 57cc chambers....I think i went with .041"

**Gto600bob** · 01-15-2012, 03:55 AM

Oh ok, I havnt chosen the cam yet that I will be putting in the car. It took me awhile just to decide on the 418. I was going with the 429ci ls3 but I still want it to be possible for me to drive it frequently if i want. Tsp told me the 4.125 stroke will be a little much for a possible daily driver. I didnt feel to comfortable having such a short skirt of a piston being put in a car that might be driven more than twice a week. I was told not to go any further than 11.5 while using pump gas, so I'll just get a fairly lumpy cam a a really high flowing head to make up for the extra point of compression. So while the block is being built I'll decide on the cam specs and the heads. Did you go with the high flow ls6 ported oil pump and a duel roller timing set?

**mark21742** · 01-15-2012, 08:53 AM

Yup, high flow melling pump and double roller chain. In my 408 the 255/263 cam acts like a 230 cam in a stock cube ls1.....very streetable, and VERY noticable lol decient idle at 900 rpms, but lots of hours of street tuning to get it perfect

**Hi-Po** · 01-15-2012, 01:16 PM

Look into the MAST medium bore or large bore LS3 heads. Depending on your bore size you could even look at the MAST LS7 heads. The MAST LS3 medium bore heads flow 351 at .600" and 370 at 700".

Don't get to caught up in flow numbers, search around for what the heavy hitters are using for heads if your trying to make big power. Cary works for MAST; same guy who had ETP going.

I'll be going with a 398" with MAST medium bore 12 degree heads for my F1A Procharger build after talking with Fraser at AES Racing Engines.

**mark21742** · 01-15-2012, 03:24 PM

I have been VERY impressed with what I have heard about Mast heads.

Hey Ron! Long time no see!

**Hi-Po** · 01-15-2012, 03:45 PM

Originally Posted by mark21742

I have been VERY impressed with what I have heard about Mast heads.

Hey Ron! Long time no see!

It really has been Mark! Sounds like you've been doing good!

**xssv** · 01-16-2012, 10:16 AM

What are the goals here? Max effort couple times a week kinda thing? Lol, sounds like a cake and eat it too scenario. What is their definition of "aggressive" cam?

Budget friendly, I'd suggest some L92s ported by WCCH. The PRC is a good head for the money but the next step up in price. Then AFR.....then Mast. FWIW, I'd pick Mast all day if you're looking for max power potential...

**Gto600bob** · 01-16-2012, 12:52 PM

My goal is to have between 550-600 at the tires N/A from the 418. With possibly a 251/259 .660/.663. I guess your right I would like to create a situation were I can have my cake and eat it too. The car won't be driven more than a couple days a week and to the track a couple times a year after the new motor is in. Ultimately I would like to make a max effort N/A car. I looked at the mast heads; they are very impressive but they still have less exaust flow than trick flow 245. I'm thinking I'll probably go with eigther afr or trick flow because I want the best flowin head for my budget of 9-10kr for the whole build. I just want to get an idea what everyone else is running on their n/a strokers.

**xssv** · 01-17-2012, 02:00 PM

Originally Posted by Gto600bob

My goal is to have between 550-600 at the tires N/A from the 418. With possibly a 251/259 .660/.663. I guess your right I would like to create a situation were I can have my cake and eat it too. The car won't be driven more than a couple days a week and to the track a couple times a year after the new motor is in. Ultimately I would like to make a max effort N/A car. I looked at the mast heads; they are very impressive but they still have less exaust flow than trick flow 245. I'm thinking I'll probably go with eigther afr or trick flow because I want the best flowin head for my budget of 9-10kr for the whole build. I just want to get an idea what everyone else is running on their n/a strokers.

That's a huge cam...as big as whats in my 460. How about small bore LS7's? Again, Mast would be first (dont keep looking at flow #'s) or TFS.