LS3 Stroker low dyno result?
Thread Starter
Teching In
Joined: Jan 2014
Posts: 4
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LS3 Stroker low dyno result? hi!
421whp @ 7100
508wnm (373lb/ft) @ 3600
specs:
Nissan Silvia S14 (sikky conversion kit)
M6 (GTO)
LS3 415cid
Scat rod, crank
Autotech pistons
10.5:1 CR
ported 243 heads
comp dual springs, hi-energy lifters, rods
ported ls2 intake
ported ls2 TB
hooker 1 7/8 longtubes
dual 3" exhaust X-pipe -> dual 3"fullflow muffler -> dual 2.5" mufflers at the end to quiet things down, (max 95dB on tracks in sweden)
comp cams 297LRR HR14 - in247 ex263 .624 114lsa
car runs great, souds great, feels fast, but, low numbers...
i was hoping to get 450 to 500whp...
im going to change the heads and intake as soon as i can afford it..=)
afr 260 (or GM-P CNC ls3 heds) and Holly mid-rise (or similar) is the future plan..
421whp @ 7100
508wnm (373lb/ft) @ 3600
specs:
Nissan Silvia S14 (sikky conversion kit)
M6 (GTO)
LS3 415cid
Scat rod, crank
Autotech pistons
10.5:1 CR
ported 243 heads
comp dual springs, hi-energy lifters, rods
ported ls2 intake
ported ls2 TB
hooker 1 7/8 longtubes
dual 3" exhaust X-pipe -> dual 3"fullflow muffler -> dual 2.5" mufflers at the end to quiet things down, (max 95dB on tracks in sweden)
comp cams 297LRR HR14 - in247 ex263 .624 114lsa
car runs great, souds great, feels fast, but, low numbers...
i was hoping to get 450 to 500whp...
im going to change the heads and intake as soon as i can afford it..=)
afr 260 (or GM-P CNC ls3 heds) and Holly mid-rise (or similar) is the future plan..
Teching In
Joined: May 2017
Posts: 27
Likes: 0
Not at all familiar with DataMite so I dont know how their numbers run ???
What I mean is.....
Dynojet is clearly the most used Dyno software and even there you can have very different results from the same run. For example the norm is either SAE or Std results. True "corrected" numbers used are normally SAE numbers, yet some tuners will give you STD numbers which are going to be about 2.6% higher. You can also get Uncorrected Numbers which will be higher that both SAE or STD results
Then you have Mustang Dynos (also very popular), these will always be substantially lower numbers than DynoJet Results. Most ad at least 10% to a Mustang Dyno to give you the final numbers, some add as much as 15%. (12% is a common number used but people will argue no matter what you use, LOL)
So......
Point being I have no clue what we're looking at here or if there is a correction factor needed to get your final results. On top of that weather, elevation, and temp, also play a huge factor on your results (and this is all assuming the Dyno Operator knows what their doing and the Dyno was done correctly). I really wouldn't be to concerned if it feels strong, runs correctly, and has a lot of power.
In any case it sounds like you have one Bad *** Car there, whats the weight of that bad boy ???
What I mean is.....
Dynojet is clearly the most used Dyno software and even there you can have very different results from the same run. For example the norm is either SAE or Std results. True "corrected" numbers used are normally SAE numbers, yet some tuners will give you STD numbers which are going to be about 2.6% higher. You can also get Uncorrected Numbers which will be higher that both SAE or STD results
Then you have Mustang Dynos (also very popular), these will always be substantially lower numbers than DynoJet Results. Most ad at least 10% to a Mustang Dyno to give you the final numbers, some add as much as 15%. (12% is a common number used but people will argue no matter what you use, LOL)
So......
Point being I have no clue what we're looking at here or if there is a correction factor needed to get your final results. On top of that weather, elevation, and temp, also play a huge factor on your results (and this is all assuming the Dyno Operator knows what their doing and the Dyno was done correctly). I really wouldn't be to concerned if it feels strong, runs correctly, and has a lot of power.
In any case it sounds like you have one Bad *** Car there, whats the weight of that bad boy ???
Depending on who ported your heads, 243 heads are great for a 5.7-6.0. For a 400+ CI motor, they're on the small side. Even a set of used factory LS3 heads will do far better in that stroker.
Also, the LS2 intake is a severe underperformer. I know getting parts in Sweden is different than here, but a fast 92 or 102 will help a good bit over that LS2.
Your cam is largeish, but that's ok if you have the compression to support it. If your compression is say 10:1, that's a problem. If you're 12:1 with that cam you'll be in good shape
Edit - I see you have plans to address heads and intake already.
Also, the LS2 intake is a severe underperformer. I know getting parts in Sweden is different than here, but a fast 92 or 102 will help a good bit over that LS2.
Your cam is largeish, but that's ok if you have the compression to support it. If your compression is say 10:1, that's a problem. If you're 12:1 with that cam you'll be in good shape
Edit - I see you have plans to address heads and intake already.
TECH Fanatic
Joined: Aug 2009
Posts: 1,845
Likes: 255
From: Coast of San Mateo County Between Pacifica & HMB
^^^^^^^^^^What Darth said +^^^^^^^^^^
I believe you will be very happy with the AFR LS3 260 Heads, I would look
At the FAST LS3 Intake with Mid-Length Runners to eliminate "Heat Soak"
On a road course, more room for Hood clearance as well. If you keep the
comp at 10.5:1, I would also change the cam to something like,
~243*/253* 112*+3*, would be a great Road Race Set-up and rip to 7200+
with great mid range as well.
Good Luck
I believe you will be very happy with the AFR LS3 260 Heads, I would look
At the FAST LS3 Intake with Mid-Length Runners to eliminate "Heat Soak"
On a road course, more room for Hood clearance as well. If you keep the
comp at 10.5:1, I would also change the cam to something like,
~243*/253* 112*+3*, would be a great Road Race Set-up and rip to 7200+
with great mid range as well.
Good Luck
Thread Starter
Teching In
Joined: Jan 2014
Posts: 4
Likes: 0
thanks for the replys.=)
car weight is around 3100lb, havent had it on scales yet
getting parts here in sweden is a bit difficult...but ebay is my friend..=)
maybe its the combo of small intake and heads and a little too low CR...
so my CR om the low side with 10.5:1 for that cam
that is with 65cc chamber
try to find or custom make heads with smaller chamber to up the CR.
at 60cc it will be around 11:1
car weight is around 3100lb, havent had it on scales yet
getting parts here in sweden is a bit difficult...but ebay is my friend..=)
maybe its the combo of small intake and heads and a little too low CR...
so my CR om the low side with 10.5:1 for that cam
that is with 65cc chamber
try to find or custom make heads with smaller chamber to up the CR.
at 60cc it will be around 11:1
Last edited by Gummisko; Sep 12, 2017 at 03:15 PM.
I'm doing some mathemagical guessing, but your pistons have about a 13cc dish in them? Because flat top pistons would put you at 12.1:1 compression, which would really surprise you I think in waking that think up. if you try to mill or weld fill your heads, you're going to be down to 53cc combustion chambers to reach even 11.8:1. But, this would bring your dynamic compression up to 8.1 or so, which you'd really feel compared to the 7.1 dynamic compression you're running now.
i if those heads are ported by a reputable porter they can clear 3oo cfm fairly easy so the heads prolly arent holding it back. that intake is no good. as mentioned,a fast 90/92 or better yet a 102 and ported and you will easily have a 500 rw car on a dynojet. that cam has a huge split that would prolly work much better with a square port head but even with those cathederals it should perform well,11:5 or alittle more compression or so would really wake it up.either way you decide to go,that light car with 500 rw should be fun.
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Verdad Gallardo Thread Starter
Teching In
Joined: Jan 2014
Posts: 4
Likes: 0
it IS very fun to drive...=)
everything is DIY ported by me, folowing guides from other porters...
found some pictures "under progress", i did not polish, but a little smoother than the pictures.
intake="hump" removal, wider cathedral, and "bullet" shape guides, smoothed around valve seats, and matchport to intake
exhaust= bigger all around, "bullet" shape guides, smoothed around valve seats, kept D-shape, matchport to exhaust
and CC matched within 3cc
intake is only wider cathedral to match heads and smoothed edges around TB
so maybe i did some thing wrong there.
everything is DIY ported by me, folowing guides from other porters...
found some pictures "under progress", i did not polish, but a little smoother than the pictures.
intake="hump" removal, wider cathedral, and "bullet" shape guides, smoothed around valve seats, and matchport to intake
exhaust= bigger all around, "bullet" shape guides, smoothed around valve seats, kept D-shape, matchport to exhaust
and CC matched within 3cc
intake is only wider cathedral to match heads and smoothed edges around TB
so maybe i did some thing wrong there.
Thread Starter
Teching In
Joined: Jan 2014
Posts: 4
Likes: 0
the top end will be changed...
i have an elbow to the left and a tight fit heat shield, and a cold air duct from the front bumper
ill take pictures of the engine bay and post
i have an elbow to the left and a tight fit heat shield, and a cold air duct from the front bumper
ill take pictures of the engine bay and post
Joined: Jul 2007
Posts: 1,503
Likes: 177
From: ELSA, South TEXAS (956) 802-7700
much truth below...
depending on who ported your heads, 243 heads are great for a 5.7-6.0. For a 400+ ci motor, they're on the small side. Even a set of used factory ls3 heads will do far better in that stroker.
Also, the ls2 intake is a severe underperformer. I know getting parts in sweden is different than here, but a fast 92 or 102 will help a good bit over that ls2.
Your cam is largeish, but that's ok if you have the compression to support it. If your compression is say 10:1, that's a problem. If you're 12:1 with that cam you'll be in good shape
edit - i see you have plans to address heads and intake already.
Also, the ls2 intake is a severe underperformer. I know getting parts in sweden is different than here, but a fast 92 or 102 will help a good bit over that ls2.
Your cam is largeish, but that's ok if you have the compression to support it. If your compression is say 10:1, that's a problem. If you're 12:1 with that cam you'll be in good shape
edit - i see you have plans to address heads and intake already.
