L92 head dyno in GM High Tech
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From: Elmhurst, IL (Chicago Suburb)
So is it just a matter of the L92's simply outflowing the LS2's heads?[/QUOTE]
Yes, I read the article and with the matching intake for the L92 they simply significantly outflowed the LS2 with its matching intake. !
Yes, I read the article and with the matching intake for the L92 they simply significantly outflowed the LS2 with its matching intake. !
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Joined: Nov 2005
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From: Arlington, TN
It would be nice if say I don't know... PRC and Ls2port works sent in some goodies to GMHP to have the test run again.
I'm thinking a set of PRC Stage 2 243's and PRC soon to be released Ported L92's with a 65cc chamber size. And get Chris over at LS2portworks to offer up a manifold and a tb (the tb could be tested on both the LS2 manifold as well as the L76 manifold).
Then we would have a clearer picture of what happens when you put ported 243's up against a ported L92 (and have them try a cam with just a little more duration on the exhaust).
It could work out as Promotional material for PRC and LS2port works while letting a magazine do the footwork of dyno testing the parts and letting everyone know what side wins.
Okay I'll quit dreaming.
Oh and the reason I listed up a ported manifold and TB is simply to try to take the weak (per say) flow of the stock LS2 manifold out of the equasion.
Tony (AFR) pointed out the LS2's manifold stock flow is low compared to the L76's manifold (and putting a FAST LSX into the mix wouldn't hurt either).
I'm thinking a set of PRC Stage 2 243's and PRC soon to be released Ported L92's with a 65cc chamber size. And get Chris over at LS2portworks to offer up a manifold and a tb (the tb could be tested on both the LS2 manifold as well as the L76 manifold).
Then we would have a clearer picture of what happens when you put ported 243's up against a ported L92 (and have them try a cam with just a little more duration on the exhaust).
It could work out as Promotional material for PRC and LS2port works while letting a magazine do the footwork of dyno testing the parts and letting everyone know what side wins.
Okay I'll quit dreaming.
Oh and the reason I listed up a ported manifold and TB is simply to try to take the weak (per say) flow of the stock LS2 manifold out of the equasion.
Tony (AFR) pointed out the LS2's manifold stock flow is low compared to the L76's manifold (and putting a FAST LSX into the mix wouldn't hurt either).
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From: Sunny London, UK
PRC is I think Texas Speed's head porting outfit.
Also for anyone who spent some time looking at the dyno logs from the comparison will notice that the stock LS2 heads outperformed the L92 heads under 3500RPM.
Now for motorway cruising, stop start traffic and general around town action, the stock LS2 heads will win.
Any track work forget it, the L92 rips.
Maybe the situation would change with a more suitable L92 cam. I think as others have mentioned the cam suited the LS2 more than the L92 in this dyno comparison. Whether the under 3500 rpm would make much difference remains to be seen.
Also for anyone who spent some time looking at the dyno logs from the comparison will notice that the stock LS2 heads outperformed the L92 heads under 3500RPM.
Now for motorway cruising, stop start traffic and general around town action, the stock LS2 heads will win.
Any track work forget it, the L92 rips.
Maybe the situation would change with a more suitable L92 cam. I think as others have mentioned the cam suited the LS2 more than the L92 in this dyno comparison. Whether the under 3500 rpm would make much difference remains to be seen.
Staging Lane
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From: under the hood
Originally Posted by ringram
Also for anyone who spent some time looking at the dyno logs from the comparison will notice that the stock LS2 heads outperformed the L92 heads under 3500RPM.
FormerVendor
Joined: Jan 2002
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From: Mpls., MN
Originally Posted by LSX Wizard
The port volume and valve size is mainly to blame for this..... blame may be a little strong and seem negative..... but we aren't gonna be mad that it works so well up higher, especially for the $$$ spent. But when the L92 heads get used on a bigger 400+ cid engine, the rpm where the L92's take over will be a fair amount sooner.
Brian
HiTech Motorsport
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From: Sunny London, UK
Its just worth bearing in mind rather than blindly throwing them on a 6L engine.
Losing the bottom 50% of useable RPM just to gain the top 50% which you might only use 5% of the time on the street needs serious consideration.
Losing the bottom 50% of useable RPM just to gain the top 50% which you might only use 5% of the time on the street needs serious consideration.
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Verdad Gallardo Staging Lane
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From: under the hood
Originally Posted by ringram
Its just worth bearing in mind rather than blindly throwing them on a 6L engine.
Losing the bottom 50% of useable RPM just to gain the top 50% which you might only use 5% of the time on the street needs serious consideration.
Losing the bottom 50% of useable RPM just to gain the top 50% which you might only use 5% of the time on the street needs serious consideration.
The know it all's know it all
Joined: Oct 2006
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Originally Posted by ringram
Its just worth bearing in mind rather than blindly throwing them on a 6L engine.
Losing the bottom 50% of useable RPM just to gain the top 50% which you might only use 5% of the time on the street needs serious consideration.
Losing the bottom 50% of useable RPM just to gain the top 50% which you might only use 5% of the time on the street needs serious consideration.
Originally Posted by michael402z06
I think most of the power losses down low are due to the lack of compression. 10.2 to 10.9 will make a difference.
Nate
Nate
Originally Posted by SStrokerAce
Well I think some people are going to be suprised as to what port size vs. port flow quality are going to do. Too bad "flow quality" is something that not to many understand.
Bret
Bret
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Bret,
No-one has to understand bad or good flow quality. ONly that with good "flow" quality that the theoretical HP per CFM usually apply and that with "bad flow quality" they dont necessarily apply.
You figure with CNC to repeat accuracy, flow manometers, wet flow testing, etc that newer cyllinder heads will not be released with "bad flow quality"...
Dennis
No-one has to understand bad or good flow quality. ONly that with good "flow" quality that the theoretical HP per CFM usually apply and that with "bad flow quality" they dont necessarily apply.
You figure with CNC to repeat accuracy, flow manometers, wet flow testing, etc that newer cyllinder heads will not be released with "bad flow quality"...
Dennis
Does anyone ever wonder why these heads look very familar to other new GM performance heads for the GEN III & IV.... these things have been around longer than most of us have OWNED our current or even a LS powered vehicle. My guess is up until Mike Chapman got GM to let him do a CNC program for the LS7 they were not destined for a truck but a car ;-) That's one of the reasons why the castings are so good in stock form and casting quality.
As far as massaging goes for them.... just like the LS7 heads you better know what the hell you are doing. These heads already move more wind with the intake attached than the motors demand, so getting high quality requardless of bench numbers that wow customers is going to make more power. (but in reality that counts on all heads, except on this forum
) You can have one hell of a small cathedral port head that has "high velocity" and something like the L92 run both of them and the quality of the L92 is going to win out over the "velocity" of the small head. In essence if you combined the two in the perfect match of both (FOR THE APPLICATION) you would be better off, but that's not going to happen anytime soon.
Bret
As far as massaging goes for them.... just like the LS7 heads you better know what the hell you are doing. These heads already move more wind with the intake attached than the motors demand, so getting high quality requardless of bench numbers that wow customers is going to make more power. (but in reality that counts on all heads, except on this forum
) You can have one hell of a small cathedral port head that has "high velocity" and something like the L92 run both of them and the quality of the L92 is going to win out over the "velocity" of the small head. In essence if you combined the two in the perfect match of both (FOR THE APPLICATION) you would be better off, but that's not going to happen anytime soon.Bret
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From: Rockfield Kentucky
Originally Posted by SStrokerAce
As far as massaging goes for them.... just like the LS7 heads you better know what the hell you are doing. These heads already move more wind with the intake attached than the motors demand, so getting high quality requardless of bench numbers that wow customers is going to make more power. (but in reality that counts on all heads, except on this forum
) You can have one hell of a small cathedral port head that has "high velocity" and something like the L92 run both of them and the quality of the L92 is going to win out over the "velocity" of the small head. In essence if you combined the two in the perfect match of both (FOR THE APPLICATION) you would be better off, but that's not going to happen anytime soon.Bret
The L92's do a very nice job for what they were designed. Now as we know most every performance modification such as cam/intake/heads will move the powerband in some manner.
Somewhere there will be a trade off. My mother would never notice the benifit from the airflow in the higher RPM band. That is why you won't see her posting in this forum.
The beauty of the L92 head is the value. It's a mass produced head that (as testing has proven) works very well in a bolt on configuration. Again for what the head does it's a one hell of a value.
What I see and what worries me are those who want to compare this head to a head designed for the aftermarket. There will be a point that people would be better served to step up to a race style head instead of going crazy on modifications of the L92 head.
A lot of vendors look to put their own "magic" on parts. In my opinion they should be very careful not to over state what improvements they will attain.
A CNC program is only as good as the guy who writes the program. The gains on some of the current production parts will be a lot less than have been found in the past. An example would be the LS7. The engineers at GM did a great job with that engine. It does exactly what they want.
Finding major improvements will be difficult. You may even lose power.
Be careful
Robin