View Poll Results: Does anyone have an engine with a L76 intake with a peak HP above 6350RPM.
Yes
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4
33.33%
No
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8
66.67%
Voters: 12. You may not vote on this poll
SDPC 416 L92 Out of Air @ 6100 RPM
#21
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Originally Posted by cybernco
Wow, I'm sorry I let this go so long without a reply.
I have Stock L92 heads with the 40Lb injectors that came with the L92 416 from SDPC.
I've got the HPTuners scan from my Dyno run, but I'm not sure how to post it here.
I think the cam selection is a very likely culpret too. Brian @ Scoggin Dickey ordered the Cam from Comp Cams as a custom cam. The specs on the cam installed are different from the one I was quoted. Maybe this has nothing at all to do with my upper RPM limit. I think that the L92/L76 setup was just too new in November last year, when I ordered the engine, to have had enough time in R & D to deliver a great cam.
Here are the specs on my cam:
![](http://i178.photobucket.com/albums/w246/cybernco/SmallerCamCard.jpg)
I wish someone would design a better intake for the L92 motor, having shorter runners. F.A.S.T. are you listening???
GHL Crossover... Hmmm, I looked at the Borla and it does the same thing at the crossover. Did you go to straight pipe and eliminate your crossover completely?
I plan on a 75 HP shot of NOS after I’ve installed in a better fuel pump and am confident of my tune.
You know, from 3000-5500 RPM's the car is a rocket ready to rip out the drive train. You gotta love torque!!!
I have Stock L92 heads with the 40Lb injectors that came with the L92 416 from SDPC.
I've got the HPTuners scan from my Dyno run, but I'm not sure how to post it here.
I think the cam selection is a very likely culpret too. Brian @ Scoggin Dickey ordered the Cam from Comp Cams as a custom cam. The specs on the cam installed are different from the one I was quoted. Maybe this has nothing at all to do with my upper RPM limit. I think that the L92/L76 setup was just too new in November last year, when I ordered the engine, to have had enough time in R & D to deliver a great cam.
Here are the specs on my cam:
![](http://i178.photobucket.com/albums/w246/cybernco/SmallerCamCard.jpg)
I wish someone would design a better intake for the L92 motor, having shorter runners. F.A.S.T. are you listening???
GHL Crossover... Hmmm, I looked at the Borla and it does the same thing at the crossover. Did you go to straight pipe and eliminate your crossover completely?
I plan on a 75 HP shot of NOS after I’ve installed in a better fuel pump and am confident of my tune.
You know, from 3000-5500 RPM's the car is a rocket ready to rip out the drive train. You gotta love torque!!!
#22
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Originally Posted by cybernco
I wish someone would design a better intake with shorter runners for the L92. F.A.S.T. are you listening???
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WHIPPLE Superchargers, Procharger, Magnuson, Powerbond Sale, HPTuners packages!, Trickflow, AFR, PRC, CHE Trunion upgrade, $100 7.400" pushrod set, Custom Cam of your choice
#23
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Originally Posted by Matt @ SDPC
It's on their "punch list"! They said they just need to finish their current project (Ford intake) and then the L76 is next!
Why can't they work on more than one at a time??
#24
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I have to say, that X-pipe does look suspicious. Have you tried dropping out the exhaust and making a dyno run? A serious exhaust restriction would account for high RPM power drop off, as well as the fact that your peak torque numbers are not real high.
Is the cam card in your post the currently installed cam? If not, what are the installed specs?
If it's cam related, the two valve events which control high-rpm extension are, in priority order, Intake valve close and Exhaust valve open. Without access to pressure volume trace data (which you can't get without mega-dollar engine dyno testing), or engine simulation software, I can't say whether your EVO is early enough, but I'd make a wild guess that it is. That leaves moving your IVC later. If you want to leave your overlap the same (for idle and drivability quality), you would increase intake duration, spread the LSA, and retard the intake center line. For instance, 240/248/113+3 (110 ICL), or 244/248/114+2 (112 ICL). This would move IVC later by 4 degrees and 8 degrees, respectively, while leaving overlap constant.
But be aware, there's no free lunch - moving your IVC later will increase reversion and therefore reduce low speed torque a bit. Depending on how you drive and what your goals are, you might find you like your current setup better.
If it were me, I'd be tempted to first drop out that X-pipe, put on ear muffs, and make a dyno pull, to eliminate that as a possibility ...
Is the cam card in your post the currently installed cam? If not, what are the installed specs?
If it's cam related, the two valve events which control high-rpm extension are, in priority order, Intake valve close and Exhaust valve open. Without access to pressure volume trace data (which you can't get without mega-dollar engine dyno testing), or engine simulation software, I can't say whether your EVO is early enough, but I'd make a wild guess that it is. That leaves moving your IVC later. If you want to leave your overlap the same (for idle and drivability quality), you would increase intake duration, spread the LSA, and retard the intake center line. For instance, 240/248/113+3 (110 ICL), or 244/248/114+2 (112 ICL). This would move IVC later by 4 degrees and 8 degrees, respectively, while leaving overlap constant.
But be aware, there's no free lunch - moving your IVC later will increase reversion and therefore reduce low speed torque a bit. Depending on how you drive and what your goals are, you might find you like your current setup better.
If it were me, I'd be tempted to first drop out that X-pipe, put on ear muffs, and make a dyno pull, to eliminate that as a possibility ...
#25
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A 416 with L92 heads needs an intake valve closing point of around 52 degrees ABDC at .050" if you're wanting a power peak above 6100 rpm (while still maintaining good mid-range torque). The cross sectional area and tuned runner length of the L76 intake will force a fairly early power peak without the proper intake valve closing point. Too early of an EVO might also make torque a little soft. It's all a balancing act. 71CamaroLS1 has some outstanding info above.
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2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
#26
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Originally Posted by cybernco
Wow, I'm sorry I let this go so long without a reply.
I have Stock L92 heads with the 40Lb injectors that came with the L92 416 from SDPC.
I'm not sure how to post the HPTuners scan file from my Dyno run on this forum.
Like several of you, I too think my cam is a very likely culprit of the upper RPM limitation. I think that the L92/L76 setup was just too new, when I ordered the engine in November last year. Not enough was known (Publicly) of what kind of cam the L92/L76 setup would really respond to.
Here are the specs on my cam:
![](http://i178.photobucket.com/albums/w246/cybernco/SmallerCamCard.jpg)
I wish someone would design a better intake with shorter runners for the L92. F.A.S.T. are you listening???
GHL Crossover... Hmmm, I looked at the Borla and it has a small crossover section too. I'm curious about this one. Did you go to straight pipe on your car and eliminate your crossover completely?
![](http://i178.photobucket.com/albums/w246/cybernco/GTOsystem.jpg)
I do plan on a 75 HP shot of NOS after I’ve installed in a better fuel pump and am confident of my tune.
You know, from 3000-5500 RPM's the car is a rocket ready to rip out the drive train. You gotta love torque!!!
I have Stock L92 heads with the 40Lb injectors that came with the L92 416 from SDPC.
I'm not sure how to post the HPTuners scan file from my Dyno run on this forum.
Like several of you, I too think my cam is a very likely culprit of the upper RPM limitation. I think that the L92/L76 setup was just too new, when I ordered the engine in November last year. Not enough was known (Publicly) of what kind of cam the L92/L76 setup would really respond to.
Here are the specs on my cam:
![](http://i178.photobucket.com/albums/w246/cybernco/SmallerCamCard.jpg)
I wish someone would design a better intake with shorter runners for the L92. F.A.S.T. are you listening???
GHL Crossover... Hmmm, I looked at the Borla and it has a small crossover section too. I'm curious about this one. Did you go to straight pipe on your car and eliminate your crossover completely?
![](http://i178.photobucket.com/albums/w246/cybernco/GTOsystem.jpg)
I do plan on a 75 HP shot of NOS after I’ve installed in a better fuel pump and am confident of my tune.
You know, from 3000-5500 RPM's the car is a rocket ready to rip out the drive train. You gotta love torque!!!
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Originally Posted by RyneZ06
this is actually my exact exhaust system i had on my car, they took a picture of it before they put it on
I can't wait to hear about your new engine.
#28
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Originally Posted by 71CamaroLS1
To really understand how intake, exhaust, and cam work together in a high-performance engine, download the user's manual for Dynomation:
http://www.proracingsim.com/download...sersManual.pdf
and read the section called Wave-Dynamics Analysis, beginning on page 231. It sums up much of the important information from my Internal Combustion Engine theory course 25 years ago, but in a much more accessible form.
Unfortunately, it's a 44MB download, so beware.
And if you or your engine guru are particularly ambitious, buy the Dynomation program itself and model your engine. You can experiment much more quickly and cheaply in software than by testing a dozen new cams ...
http://www.proracingsim.com/download...sersManual.pdf
and read the section called Wave-Dynamics Analysis, beginning on page 231. It sums up much of the important information from my Internal Combustion Engine theory course 25 years ago, but in a much more accessible form.
Unfortunately, it's a 44MB download, so beware.
And if you or your engine guru are particularly ambitious, buy the Dynomation program itself and model your engine. You can experiment much more quickly and cheaply in software than by testing a dozen new cams ...
#30
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Originally Posted by Bink
71CamaroLS1 - which Dynomation version would you suggest?
Be aware - Dynomation requires a lot more input data than tools like DynoSim - you have to have accurate data on things like intake runner/port length, port cross section, runner/port taper, for instance. And it's definitely a garbage in/garbage out kind of deal
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#31
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Here's an interesting comparison of torque/hp curves for a fairly similar combination. Something is very different at the low and high ends of the curves.
It's currently active thread.
https://ls1tech.com/forums/showpost....93&postcount=1
It's currently active thread.
https://ls1tech.com/forums/showpost....93&postcount=1
#32
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Originally Posted by Old SStroker
Here's an interesting comparison of torque/hp curves for a fairly similar combination. Something is very different at the low and high ends of the curves.
It's currently active thread.
https://ls1tech.com/forums/showpost....93&postcount=1
It's currently active thread.
https://ls1tech.com/forums/showpost....93&postcount=1
https://ls1tech.com/forums/showpost....&postcount=108
WKMCD is very competant; his advice is always solid.
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Originally Posted by cybernco
Here's his final dyno.
https://ls1tech.com/forums/showpost....&postcount=108
WKMCD is very competant; his advice is always solid.
https://ls1tech.com/forums/showpost....&postcount=108
WKMCD is very competant; his advice is always solid.
Example, I just had my old 408" on the dyno in another car, clogged cats cost over 40 rwhp and rwt. In addition, the PCM was pulling timing like crazy, max of 16' advance. Your scans will tell the story.
#34
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Originally Posted by 71CamaroLS1
I've not used the ProTools version - but the base version of Dynomation is already a pretty advanced piece of software, so my guess is unless you're a full-time engine builder/designer you'd probably never get to the features in ProTools.
Be aware - Dynomation requires a lot more input data than tools like DynoSim - you have to have accurate data on things like intake runner/port length, port cross section, runner/port taper, for instance. And it's definitely a garbage in/garbage out kind of deal
But for a geek like me, it's pretty addictive to play around with combos and watch the changes in things like pressure/volume traces and intake/exhaust velocities ...
Be aware - Dynomation requires a lot more input data than tools like DynoSim - you have to have accurate data on things like intake runner/port length, port cross section, runner/port taper, for instance. And it's definitely a garbage in/garbage out kind of deal
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
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Is there a place where I can access the neccessary data for the LS1/6/7 ??
#35
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I've never tried to find any data on these motors ... but I'm about to try, since I'm planning a 427 short/LS7 head build with carb-style intake for a '69 Camaro project, and there is very little info available for camming that combo. Even with the plastic intake LS7, the aftermarket tuners seem to be all over the map as to what works best - or to put it more specifically, they seem to get fairly similar results with wildly different grinds, e.g. Katech torquer 220/244/110 and LG G7X3 228/240/118.
#36
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Originally Posted by 71CamaroLS1
I've never tried to find any data on these motors ... but I'm about to try, since I'm planning a 427 short/LS7 head build with carb-style intake for a '69 Camaro project, and there is very little info available for camming that combo. Even with the plastic intake LS7, the aftermarket tuners seem to be all over the map as to what works best - or to put it more specifically, they seem to get fairly similar results with wildly different grinds, e.g. Katech torquer 220/244/110 and LG G7X3 228/240/118.
![Icon Rolleyes](https://ls1tech.com/forums/images/smilies2/icon_rolleyes.gif)
Plus, I'd enjoy the learning experience
![Grin](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_grin.gif)
Now to buy the Dynomation.
#37
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Originally Posted by 2c5s
See if you can get your dyno graph in SAE and not STD. What type of dyno was used? How does the car feel? Is it lazy or fast, faster than before? What was the A/F, timing on the runs? Do you have access to any of the scans while on the dyno?
Example, I just had my old 408" on the dyno in another car, clogged cats cost over 40 rwhp and rwt. In addition, the PCM was pulling timing like crazy, max of 16' advance. Your scans will tell the story.
Example, I just had my old 408" on the dyno in another car, clogged cats cost over 40 rwhp and rwt. In addition, the PCM was pulling timing like crazy, max of 16' advance. Your scans will tell the story.
#38
Launching!
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The more combos I read about using the L76/L92 combo, the more it appears that the L76 is limiting peak RPM, either through runner length or lack of runner volume or both (it does restrict airflow some as well, but that doesn't account for why so many different cam/cid combos all peak out by about 6100 - 6300).
Here is further evidence:
http://www.tpis.com/plog/index.php?o...Id=29&blogId=1
However, designing an intake to overcome the L76 limitations will be tricky. The L76 design clearly "crutches" the big L92 intake port by using finite amplitude wave tuning to augment torque. The alternative intakes I've seen so far - the sheetmetal intakes and the Livernois carb intake - all lose quite a bit of mid-range torque in order to gain on the top end. It will probably take Wilson and FAST collaborating again to design a minimal compromises intake ...
Here is further evidence:
http://www.tpis.com/plog/index.php?o...Id=29&blogId=1
However, designing an intake to overcome the L76 limitations will be tricky. The L76 design clearly "crutches" the big L92 intake port by using finite amplitude wave tuning to augment torque. The alternative intakes I've seen so far - the sheetmetal intakes and the Livernois carb intake - all lose quite a bit of mid-range torque in order to gain on the top end. It will probably take Wilson and FAST collaborating again to design a minimal compromises intake ...
#39
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TPI Specialties has a new intake for the L92 & LS7 with cnc ported runner & high flow fuel rails. A bit pricey with s list price of $2400.00 with injectors & fuel rails all aluminum. www.tpis.com custom fab type unit. They say it clears the hood & straight bolt-on. LOL
http://www.tpis.com/plog/index.php?o...Id=28&blogId=1
http://www.tpis.com/plog/index.php?o...Id=28&blogId=1
#40
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As a exhaust fab guy, I would have to say that X is not the right way to do it. The X pipe config. is one of a balance tube or port NOT a transfer from side to side, by doing this they are actually reducing the size of the system in the middle of the X. Look at how some others do it like Borla, their X is done properly, the hole between the two sweeps in the X or the merge point should only be 50ish percent of the tube size to get it proper, any more or less does not seem to work well, I have seen this and also learned it from an EXPERT exhaust guy, John @ Hi-Tech exhaust, that man builds some MONSTEROUS power building systems and headers. I saw his headers in a back to back test on the same day same dyno make 80ftlbs. more than a 1 7/8" Hooker Super comp header on a 434" LSX engine! Just my $.02
-Bryan
-Bryan