403ci Head Questions
403ci Head Questions I have a Ls2 block being assembled with a 403ci assembly using Wiseco -8cc pistons and plan on spraying a 300 shot. My current Ls1 has a set of AI 226cc 243 heads with 63cc chambers.
My question is how much am I leaving on the table using these heads? Of course id love a set of Tfs 235's but the budget isnt there right now. Down the road I'd love to go bigger if its worth it. Anyone have any imput?
My question is how much am I leaving on the table using these heads? Of course id love a set of Tfs 235's but the budget isnt there right now. Down the road I'd love to go bigger if its worth it. Anyone have any imput?
I think those heads are going to be small for a 400ci engine. It would be a fun combo for a street car with lots of low end power, but I don't think that's what you would want when you're on a 300shot though. Depending on the cam, I doubt you will break 480whp NA.
If you're going to go racing, I would look at some ported LS3 heads. I think the larger valves and cross sectional area will help feed that engine at higher RPM and maybe soften the low end to help with traction. 550whp NA with a intelligently selected cam isn't unreasonable.
If you're going to go racing, I would look at some ported LS3 heads. I think the larger valves and cross sectional area will help feed that engine at higher RPM and maybe soften the low end to help with traction. 550whp NA with a intelligently selected cam isn't unreasonable.
Depending on budget... TFS 255s, MAST 255s... or step up to the MAST 265 LS7 heads.
I think with that kind of nitrous, you want the big runner square port stuff and an aftermarket casting.
I think with that kind of nitrous, you want the big runner square port stuff and an aftermarket casting.
Thanks for the insight guys. The cam I plan to run is a BTR stroker grind for nitrous. 251/266 63x/595 112+4. I will run the heads I have and see how the combo performs and save up for a nice set of heads down the road.
My lil ol' HCI Ls1 runs 12.1 on motor and 10.76 on a 175 shot... Thats with a super tight nitrous converter as you can see by the slow NA ET... Since then Ive upgraded to a plate and a 225 shot.
My lil ol' HCI Ls1 runs 12.1 on motor and 10.76 on a 175 shot... Thats with a super tight nitrous converter as you can see by the slow NA ET... Since then Ive upgraded to a plate and a 225 shot.
TECH Addict
Joined: Jul 2013
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From: Portland, Oregon
Absolutely use what you have now. Those AI 226's are going to be a blast while you save up for your dart ls3 heads.
Check out speedtrigger's 403, if you haven't already. It's inspiring, to say the least.
Check out speedtrigger's 403, if you haven't already. It's inspiring, to say the least.
Below is the reply from A.I. in regards to my heads and what other options would really entail. I thought it was a good read.
Thanks for taking the time to email! That head will support around 500-525rwhp or so NA w/ a HR cam, so you may find it will work out just fine since you’ve got a power adder app. If we re-CNC the larger 232cc ports + move to a 2.055” intake then it’ll gain another 20hp or so, but at that point we’re totally re-machining the head so it ends up at $1395 including a set of Manley Racemaster 2.055” stainless intake valves.
At that point you can usually sell the 226’s & spend about the same $ going to something like our 230cc head we cut in a TFS porter casting, or some of the newer stuff I’ll add to the site over the next couple months if you aren’t in a hurry. Going to the 280cc CNC’d LS3’s is an option ($2295 including new GM heads, CNC work, and a BTR dual spring kit), but that would obviously require another intake. Let me know what you think; thanks!
Thanks for taking the time to email! That head will support around 500-525rwhp or so NA w/ a HR cam, so you may find it will work out just fine since you’ve got a power adder app. If we re-CNC the larger 232cc ports + move to a 2.055” intake then it’ll gain another 20hp or so, but at that point we’re totally re-machining the head so it ends up at $1395 including a set of Manley Racemaster 2.055” stainless intake valves.
At that point you can usually sell the 226’s & spend about the same $ going to something like our 230cc head we cut in a TFS porter casting, or some of the newer stuff I’ll add to the site over the next couple months if you aren’t in a hurry. Going to the 280cc CNC’d LS3’s is an option ($2295 including new GM heads, CNC work, and a BTR dual spring kit), but that would obviously require another intake. Let me know what you think; thanks!
