6.5L + 8.5:1 c/r + 18psi = 1265 rwhp / 1103 rwtq?
03-11-2011 | 05:38 PM
#16
Rennlist Member
Joined: Nov 2005
Posts: 861
Likes: 1
From: NorCal - Bay Area
have to say, it's just the fun of having a 928.
Sure, go Renegade conversion or just change platform from a 928 all together...honestly, there are not that many 928's that will pull a stock C6/ZO6, if that's what floats your boat.
But look at how cool the efforts by Carl or Todd or Louie or Mike and so many others are. Keeping a 928 a 928, with trick mods that are usually available for other 928 owners to enjoy. Similar to why Chevy guys are Chevy guys and Ford guys are Ford guys.
Gotta think that a 500hp NA stroker from Greg or a simple 350hp 16v stage1 CS kit from Tim is pretty cool - lots of range for what makes "your" 928 experience unique and enjoyable. Specifically with Carl's current landspeed effort, it's interesting to see the progress and results from a 928 as a 928.
Sure, go Renegade conversion or just change platform from a 928 all together...honestly, there are not that many 928's that will pull a stock C6/ZO6, if that's what floats your boat.
But look at how cool the efforts by Carl or Todd or Louie or Mike and so many others are. Keeping a 928 a 928, with trick mods that are usually available for other 928 owners to enjoy. Similar to why Chevy guys are Chevy guys and Ford guys are Ford guys.
Gotta think that a 500hp NA stroker from Greg or a simple 350hp 16v stage1 CS kit from Tim is pretty cool - lots of range for what makes "your" 928 experience unique and enjoyable. Specifically with Carl's current landspeed effort, it's interesting to see the progress and results from a 928 as a 928.
03-11-2011 | 05:39 PM
#17
Three Wheelin'
Joined: Jun 2005
Posts: 1,741
Likes: 1
From: Bournemouth, Dorset, UK.
Hi 
Interesting thread and am not totally sure I should contibute to it as every time I do here I seem to get a roasting
Anyway, I will try and keep this technical and hope for the best...
On my 16 valve engine, i have run a LOT of Nitrous....and I mean well over 1000 hp including my engines 310 to 330 ish...
Now...as far as the intake valves are concerned I cannot comment as Nitrous sort of cheats there by passing the intake valves as liquid Nitrous....
On the other hand , I can comment on the exhaust valves and revs....
There is nothing in my standard exhaust valves that stops 1000 hp plus exiting the heads, my exhaust system after the heads is different from most to allow that huge amount of exhaust gases to exit out the back though... important in Nitrous... my exhaust system is as follows... standard headers, then NO CATS or front boxes at all....NO middle resonators at all..... 3 inch twin race pipe both sides going to a single Paul Anderson Race straight through box at the rear....so basically I have ONE rear straight through box and nothing else....its a little (LOT) too loud as a daily driver...think 110 to 130 DB ..but huge fun
Revs.... I had the revlimiter removed by the famous John Speake and the limit is now 9700... it was never intended to reach those revs but I have regularly run it at 7500 plus and over 8000 a few times with no problems at all....
I hope this helps the discussion...
All the best Brett
Interesting thread and am not totally sure I should contibute to it as every time I do here I seem to get a roasting
Anyway, I will try and keep this technical and hope for the best...
On my 16 valve engine, i have run a LOT of Nitrous....and I mean well over 1000 hp including my engines 310 to 330 ish...
Now...as far as the intake valves are concerned I cannot comment as Nitrous sort of cheats there by passing the intake valves as liquid Nitrous....
On the other hand , I can comment on the exhaust valves and revs....
There is nothing in my standard exhaust valves that stops 1000 hp plus exiting the heads, my exhaust system after the heads is different from most to allow that huge amount of exhaust gases to exit out the back though... important in Nitrous... my exhaust system is as follows... standard headers, then NO CATS or front boxes at all....NO middle resonators at all..... 3 inch twin race pipe both sides going to a single Paul Anderson Race straight through box at the rear....so basically I have ONE rear straight through box and nothing else....its a little (LOT) too loud as a daily driver...think 110 to 130 DB ..but huge fun
Revs.... I had the revlimiter removed by the famous John Speake and the limit is now 9700... it was never intended to reach those revs but I have regularly run it at 7500 plus and over 8000 a few times with no problems at all....
I hope this helps the discussion...
All the best Brett
03-11-2011 | 05:40 PM
#18
Racer
Joined: Jan 2009
Posts: 326
Likes: 1
From: Adelaide South Australia'79 5spd twin turbo
He is right Hacker, X amount of air = y horsepower, Air,not psi. it is easy to confuse the two, but it is the weight of air that is the determining factor, not pressure.
As he points out the more correctly matched turbo will produce the right figures as it doesn't heat the air as much.
Cheers Roy
As he points out the more correctly matched turbo will produce the right figures as it doesn't heat the air as much.
Cheers Roy
03-11-2011 | 05:52 PM
#20
Administrator
Joined: Aug 2001
Posts: 1,628
Likes: 2,248
From: Up Nort
03-11-2011 | 06:32 PM
#21
Racer
Joined: Jan 2009
Posts: 326
Likes: 1
From: Adelaide South Australia'79 5spd twin turbo
Oh ! Cheers :-)
Ah, I had always wondered what Hacker- Pschorr, was all about, till I was in Munchen a couple of years back and there it was right in front of me!
Prost, Roy
Ah, I had always wondered what Hacker- Pschorr, was all about, till I was in Munchen a couple of years back and there it was right in front of me!
Prost, Roy
03-11-2011 | 06:43 PM
#22
Burning Brakes
Joined: Jun 2008
Posts: 909
Likes: 0
From: NY
If you own a (modified) C6 Corvette.
I don't get this.
Many 928 owners have worked long and hard and spent serious $$$ and R&D hours to create mods and methods to make our 928's lay down big horsepower.
Carl has posted the numbers on his supercharged stroker he built for Bonneville, which has put down the highest recorded HP numbers by any 928 block to date.
I've purposely started a new thread, because I don't want this taken to be a comment on Carl's build in any way, which is quite an accomplishment.
But, check out the specs on this vette.
http://www.planetlsx.com/vehicles/It..._Boom_Pow/135#
It has a de-stroked LS7, the displacement has been reduced to 400c.i., it too has 8.5 c/r, and 18 psi of boost, yet it made 1265 rwhp / 1103 rwtq.
I believe these are the same short block dimensions and boost levels as the 928MS engine.
At only 8 psi, the bowtie still made 835 rwhp / 673 rwtq, besting our 928 HP king with 10 less PSI of boost.
So, what is going on here? The 928MS motor has clearly taken every advantage possible to create as much HP as possible. The vette has done the same. The article mentions that the vette heads flow upwards of 400 cfm, which I believe is about 15% higher than the best 928 heads have flowed.
So is that where the answer lies?
If we were able to bolt on a set of 400 cfm heads would the Bonneville car instantly gain a 40% increase in RWHP and be a 1000 rwhp monster?
The reason I'm asking at all, is that it seems that we 928 owners really have to work hard for our horsepower. I know the rational is that our engines are so well optimized from the factory that there isn't much left on the table. Still, it makes me wonder why the 928 motor seems resistant to making big power easily.
Comments?
I don't get this.
Many 928 owners have worked long and hard and spent serious $$$ and R&D hours to create mods and methods to make our 928's lay down big horsepower.
Carl has posted the numbers on his supercharged stroker he built for Bonneville, which has put down the highest recorded HP numbers by any 928 block to date.
I've purposely started a new thread, because I don't want this taken to be a comment on Carl's build in any way, which is quite an accomplishment.
But, check out the specs on this vette.
http://www.planetlsx.com/vehicles/It..._Boom_Pow/135#
It has a de-stroked LS7, the displacement has been reduced to 400c.i., it too has 8.5 c/r, and 18 psi of boost, yet it made 1265 rwhp / 1103 rwtq.
I believe these are the same short block dimensions and boost levels as the 928MS engine.
At only 8 psi, the bowtie still made 835 rwhp / 673 rwtq, besting our 928 HP king with 10 less PSI of boost.
So, what is going on here? The 928MS motor has clearly taken every advantage possible to create as much HP as possible. The vette has done the same. The article mentions that the vette heads flow upwards of 400 cfm, which I believe is about 15% higher than the best 928 heads have flowed.
So is that where the answer lies?
If we were able to bolt on a set of 400 cfm heads would the Bonneville car instantly gain a 40% increase in RWHP and be a 1000 rwhp monster?
The reason I'm asking at all, is that it seems that we 928 owners really have to work hard for our horsepower. I know the rational is that our engines are so well optimized from the factory that there isn't much left on the table. Still, it makes me wonder why the 928 motor seems resistant to making big power easily.
Comments?
Look at normally asperated motorcycle engines thats where the real factory horsepower per cubic inches are.
Stock factory engines are 190hp and getting close to 200hp now with 1000cc
1000cc/16.37=61 cu in.
190hp/61cu in=3.15 horsepower per cubic inch
If we could get that out of a 302cu in motor we would be looking at over 950hp pushing close to 1000hp without a supercharger or turbo.
The 928 is an old design compared to todays car engines head flow,cams,intakes etc and we are lucky enough to have some guys out there doing alot of new ideas for the 928's
03-11-2011 | 08:12 PM
#23
Three Wheelin'
Joined: Aug 2006
Posts: 1,765
Likes: 1
From: Atlanta
Remember the L-88 427 Chevy engines, from about 1969? 425 claimed horsepower. Everyone thought that Chevy might have understated those numbers and they "thought" that those engines really made about 500hp.
I had a buddy that assembled one of those...with original pieces. It makes 700hp, at the rear wheels, by today's standards....go figure.
I had a buddy that assembled one of those...with original pieces. It makes 700hp, at the rear wheels, by today's standards....go figure.
I'd like to hear the same about the Buick GS 455 that was "rated" at 360 hp. It was among the quickest cars of the era. It would be fun to gather all the parts and find out! Hmm....
03-11-2011 | 08:58 PM
#24
Rest in Peace
Rennlist Member
Rennlist Member
Joined: May 2006
Posts: 9,903
Likes: 2
From: Bird lover in Sharpsburg
The original LS7's were monsters, big torque monsters, I have broken things that people did not think could be broken, snapped the snout off of several TCI race convertors, broken the frame loop at the front right 2 times.
Take a look at a real LS6 or 7 Chevelle around the windshield, ten bucks says it has cracks on the A pillar.
The real difference is number of people and money.
It was a very short time after the LXs engines came out that you could buy Billet blocks and heads.
While being a outsider on the search for really high HP 928's, I suspect some are getting close to the point of reaching the limit of what the block will take.
I am a little surprised that a certain GA master machinist has not went down the billet block road, good god knows he has made some really trick stuff.
PS Mike, thanks for the loan of the crank, how did you find Uncle Mitch.
i hope he was having a good day.
EDIT, about the only difference between the old L88 and the LS7's we aluminum head of a open chamber design. (for you hacker)
One other thing, if you could get ten thousand miles out of one of these motors on the street, then you were living right and kept the block warm and used special start procedures.
They would wipe the lobes off of a cam in a heart beat.
Last edited by blown 87; 03-11-2011 at 09:34 PM.
03-11-2011 | 10:53 PM
#25
Drifting
Joined: Oct 2009
Posts: 2,638
Likes: 2
From: Alberta, Canada
OH! Man you guys are not kidding.
They called me Dr Olds.
Start with A 67 455 casting as the mains webs are thicker for cross bolting.
Line bore, install main sleeves and fit with a 425 steel crank with bored and radius oil holes.
Bottom end is the week part on those big blocks.
Bal and Blu so it will rev
7 inch rods
use C casting heads and the largest valves that fit (cc with mild porting)
6.6 lift /328 cam and it will need to idle at 1500 rpm
Torquer intake and a 1080 cfm Holly and the engine will dyno at 650 HP without boost
Run a 3200 stall convertor, shift at 7200 and you have a 10 sec cutlass. Latter bars and slicks are a requirement.
Like said a few post back, get the 928 to breath (big cams and ported head) better intake, free flowing exhaust. to make big HP.
I don't know how much the block will handle.
but IMHO the heads and cams especially the cams are not radical enough to make that kind of HP without all kinds of boost.
BTW 12psi put it just over 1200 but it spun a main and detonated a week later (2 months racing before was fine but 1 week after boost, to much)
Last edited by 928mac; 03-11-2011 at 11:11 PM.
03-12-2011 | 01:12 AM
#26
Drifting
Joined: Oct 2009
Posts: 2,638
Likes: 2
From: Alberta, Canada
03-12-2011 | 09:39 AM
#28
Three Wheelin'
Joined: Nov 2003
Posts: 1,481
Likes: 1
From: Doylestown, PA
If you own a (modified) C6 Corvette.
I don't get this.
Many 928 owners have worked long and hard and spent serious $$$ and R&D hours to create mods and methods to make our 928's lay down big horsepower.
Carl has posted the numbers on his supercharged stroker he built for Bonneville, which has put down the highest recorded HP numbers by any 928 block to date.
I've purposely started a new thread, because I don't want this taken to be a comment on Carl's build in any way, which is quite an accomplishment.
But, check out the specs on this vette.
http://www.planetlsx.com/vehicles/It..._Boom_Pow/135#
It has a de-stroked LS7, the displacement has been reduced to 400c.i., it too has 8.5 c/r, and 18 psi of boost, yet it made 1265 rwhp / 1103 rwtq.
I believe these are the same short block dimensions and boost levels as the 928MS engine.
At only 8 psi, the bowtie still made 835 rwhp / 673 rwtq, besting our 928 HP king with 10 less PSI of boost.
So, what is going on here? The 928MS motor has clearly taken every advantage possible to create as much HP as possible. The vette has done the same. The article mentions that the vette heads flow upwards of 400 cfm, which I believe is about 15% higher than the best 928 heads have flowed.
So is that where the answer lies?
If we were able to bolt on a set of 400 cfm heads would the Bonneville car instantly gain a 40% increase in RWHP and be a 1000 rwhp monster?
The reason I'm asking at all, is that it seems that we 928 owners really have to work hard for our horsepower. I know the rational is that our engines are so well optimized from the factory that there isn't much left on the table. Still, it makes me wonder why the 928 motor seems resistant to making big power easily.
Comments?
I don't get this.
Many 928 owners have worked long and hard and spent serious $$$ and R&D hours to create mods and methods to make our 928's lay down big horsepower.
Carl has posted the numbers on his supercharged stroker he built for Bonneville, which has put down the highest recorded HP numbers by any 928 block to date.
I've purposely started a new thread, because I don't want this taken to be a comment on Carl's build in any way, which is quite an accomplishment.
But, check out the specs on this vette.
http://www.planetlsx.com/vehicles/It..._Boom_Pow/135#
It has a de-stroked LS7, the displacement has been reduced to 400c.i., it too has 8.5 c/r, and 18 psi of boost, yet it made 1265 rwhp / 1103 rwtq.
I believe these are the same short block dimensions and boost levels as the 928MS engine.
At only 8 psi, the bowtie still made 835 rwhp / 673 rwtq, besting our 928 HP king with 10 less PSI of boost.
So, what is going on here? The 928MS motor has clearly taken every advantage possible to create as much HP as possible. The vette has done the same. The article mentions that the vette heads flow upwards of 400 cfm, which I believe is about 15% higher than the best 928 heads have flowed.
So is that where the answer lies?
If we were able to bolt on a set of 400 cfm heads would the Bonneville car instantly gain a 40% increase in RWHP and be a 1000 rwhp monster?
The reason I'm asking at all, is that it seems that we 928 owners really have to work hard for our horsepower. I know the rational is that our engines are so well optimized from the factory that there isn't much left on the table. Still, it makes me wonder why the 928 motor seems resistant to making big power easily.
Comments?
03-12-2011 | 10:08 AM
#29
Race Car
Joined: Dec 2003
Posts: 4,477
Likes: 4
From: Atlanta, GA
You can only compare horsepower if tested on the same day, with the same dyno, with the same type of tires (if testing rear wheel horsepower), at the same pressures.
My really good stroker engines (with stock style intakes) make about 420 at the rear wheels..with a "correctly" calibrated dyno....the only numbers I choose to deal with. It is simply amazing to watch one of those strokers "suck the doorknobs" off of a "600 horsepower" supercharged thing.
Figure that out.
My really good stroker engines (with stock style intakes) make about 420 at the rear wheels..with a "correctly" calibrated dyno....the only numbers I choose to deal with. It is simply amazing to watch one of those strokers "suck the doorknobs" off of a "600 horsepower" supercharged thing.
Figure that out.
Dan
'91 928GT S/C
475hp/460lb.ft
03-12-2011 | 12:22 PM
#30
Drifting
Joined: Nov 2006
Posts: 2,973
Likes: 1
From: Farmington Hills, MI