408ci build, expectations/suggestion.......
I definitely think there is something holding it back intake wise. My 6.0L LQ4 with L92 heads and a 222/226 .597/.598 112LSA cam pulls 98-99Kpa at WOT. I could be wrong about my assumption, but hey what do I know lol.
BTW, that curve does look F-in beautiful. I hope my 408 looks that good.
BTW, that curve does look F-in beautiful. I hope my 408 looks that good.
TECH Addict
Joined: Sep 2009
Posts: 2,481
Likes: 5
From: PA/MD
You are right black00, but I thought as long as it wad over 90kpa it was a small enough restriction to not make that much of a difference......but I have been wrong before 
If the car is still at the dyno try taking your MAF out, out in a 4" pipe, and try it in SD mode.
If the car is still at the dyno try taking your MAF out, out in a 4" pipe, and try it in SD mode.
Doubled Checked the cars Ive tuned on the KPA.
Under 5000k they are all 95kpa and above. But above 5000rpm they are 92-96KPA (N/A cars).
They have dynoed on this exact same dyno and had Very impressive results.
Not ruling it out just going off what I can see. I think the Volant Twin Cone might be the biggest restriction since it necks down alot. Owner of the Car said they tried an SLP Lid and intake on the car when on the dyno without any results tho. (Dont know I wasnt there)
Under 5000k they are all 95kpa and above. But above 5000rpm they are 92-96KPA (N/A cars).
They have dynoed on this exact same dyno and had Very impressive results.
Not ruling it out just going off what I can see. I think the Volant Twin Cone might be the biggest restriction since it necks down alot. Owner of the Car said they tried an SLP Lid and intake on the car when on the dyno without any results tho. (Dont know I wasnt there)
Well judging by the dyno graph and the tune i posted, i would say the tb is opening up 100% if not the afr wouldnt have taken the drastic plunge from stoich (14.7afr) down to full power enrichment (12.9). The tps is what tells the pcm to add the extra fuel for power enrichment.
I would say power is low. My 102/102 setup on my 346 sits at about 99kpa on a dyno and 102 on the freeway. :-) The heads/cam could be what is really hurting you because it seems the engine just runs out of steam on the peak. Right around 4800 rpm is where it seems the engine is trailing off.
Well judging by the dyno graph and the tune i posted, i would say the tb is opening up 100% if not the afr wouldnt have taken the drastic plunge from stoich (14.7afr) down to full power enrichment (12.9). The tps is what tells the pcm to add the extra fuel for power enrichment.
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you want to know how much restriction if any you have ,turn the key on and dont start the car, start the scanner look to see what it reads on the map without the engine running and compare it to your wide open throttle number!
TECH Fanatic
Joined: Nov 2001
Posts: 1,027
Likes: 2
From: KS
Unless those heads don't flow crap they are enough. I don't care if the heads are ported 317, 853, 241's they should be enough. I wish I could stick one on my flow bench. I have done many heads for 408 combo's. 525 to 550 rwhp with that cam size is normal. I can't believe that's all it made. My 347 on pump gas made 512 rwhp and ran high 10's with ported 243's.
Something is off. Rings got washed out or something.
Something is off. Rings got washed out or something.
OK.
Also see that the 3.91's are actually 4.10's, which is even more of a contributor to reduced numbers.
Don't know the RPM range of that cam, but thought that those longer duration high lift cams were designed for power up to 6800-7K RPM, no? I would look into this.
Also see that the 3.91's are actually 4.10's, which is even more of a contributor to reduced numbers.
Don't know the RPM range of that cam, but thought that those longer duration high lift cams were designed for power up to 6800-7K RPM, no? I would look into this.
^ are u being sarcastic?
So far i think its the lowest powered 408 in ls1tech history! Still struggling to figure out what the problem is for sure
https://ls1tech.com/forums/dynamomet...results-2.html
Have another thread going here looking for answers ^
So far i think its the lowest powered 408 in ls1tech history! Still struggling to figure out what the problem is for sure
https://ls1tech.com/forums/dynamomet...results-2.html
Have another thread going here looking for answers ^
Last edited by 06X6spdGTO; May 22, 2012 at 07:35 PM.
Cranking Compression Ratio Results:
With the throttle blade cracked open while cranking (Front to Back)
Drivers Side: Passenger Side:
195 200
198 200
200 198
200 198
dont really know what you mean by power range of the cam.
With the throttle blade cracked open while cranking (Front to Back)
Drivers Side: Passenger Side:
195 200
198 200
200 198
200 198
dont really know what you mean by power range of the cam.