Race Engine Built
09-26-2007, 04:43 PM
#1
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Thread Starter
Race Engine Built
I recently acquired the last GTS engine built by Porsche. Yes, the very last one, which used to sit on a palette in the factory https://rennlist.com/forums/showthre...hlight=EURO928
This baby is going into my GT-based race car, but I have two basic questions:
1. Drilling the crank - do I really need to do it? I think I will be reving it to 7200rpm max and I have a proven dry sump system installed.
2. Exhaust - I would go ahead and get the 928 International headers, but I am stuck with regards to the rest of the system - what diameter pipes do I need bearing in mind that I will still have a 5.4ltr engine. 2.5" dual all the way back or 3.5" single?
Many thanks in advance to all the racers out there,
Alex
p.s. I am getting 968 intake valves and GT or sharper cams installed. Displacement has to stay stock as I cannot go over 6ltrs and I don't want to bore out the block to accept the 104.5mm 968 pistons. Hoping to get around 400/410bhp on the crank with everything...
This baby is going into my GT-based race car, but I have two basic questions:
1. Drilling the crank - do I really need to do it? I think I will be reving it to 7200rpm max and I have a proven dry sump system installed.
2. Exhaust - I would go ahead and get the 928 International headers, but I am stuck with regards to the rest of the system - what diameter pipes do I need bearing in mind that I will still have a 5.4ltr engine. 2.5" dual all the way back or 3.5" single?
Many thanks in advance to all the racers out there,
Alex
p.s. I am getting 968 intake valves and GT or sharper cams installed. Displacement has to stay stock as I cannot go over 6ltrs and I don't want to bore out the block to accept the 104.5mm 968 pistons. Hoping to get around 400/410bhp on the crank with everything...
Last edited by Cheburator; 09-26-2007 at 06:49 PM. Reason: because I can't spell :)
09-26-2007, 05:29 PM
#4
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Originally Posted by John
Are the rods ok for racing? I thought the GTS rods were not the greatest.
09-26-2007, 06:53 PM
#5
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Thread Starter
Now, please tell me about the crank and the exhaust
Alex
09-26-2007, 07:18 PM
#6
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The single exhaust is what Mark A. runs it is a bit lighter weight . Personally, I would want to modify the oiling path of the crank....Anderson has had zero oiling problems with the modified oiling AND dry sump...
09-26-2007, 07:25 PM
#7
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alex
go for it
Marton
I am not sure if it was the last GTS motor built by Porsche; it was certainly the last GTS motor that the factory had available for sale - I was one of the many that photographed it in 2002....
Marton
go for it
Marton
I am not sure if it was the last GTS motor built by Porsche; it was certainly the last GTS motor that the factory had available for sale - I was one of the many that photographed it in 2002....
Marton
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09-26-2007, 07:54 PM
#8
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But I could be wrong....
09-26-2007, 09:37 PM
#9
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Kinda seems a shame to race this last GTS engine in a way. Especially since it will need to be modified to live in a racing environment. But that's just me...
From the research I've done and with my conversations with Mark Anderson and others, a drilled crank and a seperate oiling enhancer, accusump or better yet a drysump, would be needed for higher than normal RPM and G load longevity. A crank scraper, enhanced oil breathing plumbing and type of oil all seem to be involved too. Even with all these mods the engine can still grenade for other reasons. "Thats' racing!" is the usual remark after a catastrophic event.
Constantine
From the research I've done and with my conversations with Mark Anderson and others, a drilled crank and a seperate oiling enhancer, accusump or better yet a drysump, would be needed for higher than normal RPM and G load longevity. A crank scraper, enhanced oil breathing plumbing and type of oil all seem to be involved too. Even with all these mods the engine can still grenade for other reasons. "Thats' racing!" is the usual remark after a catastrophic event.
Constantine
09-26-2007, 10:18 PM
#11
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If you are planning to track the car and lean on the motor hard, imo you would be taking a huge gamble by not cross drilling the crank. I was on the fence with my track car motor and decided after speaking with the guys that have raced these cars for several years, I'd be foolish not to do so. Actually both of my engines have drilled cranks.
09-27-2007, 12:11 AM
#12
Race Director
What rpm's does Mark shift at.... I thought he ran GT like rpm's so his fuel cutoff should be 6800rpm right?
09-27-2007, 12:46 AM
#13
Former Sponsor
Drill the crank. Drill the crank. Drill the crank.
Rods should be fine.
Why would your stock motor with exhaust make 410hp? I doubt the factory left that much horsepower just sitting there untapped.
Rods should be fine.
Why would your stock motor with exhaust make 410hp? I doubt the factory left that much horsepower just sitting there untapped.
09-27-2007, 12:55 AM
#15
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shift at 6500rpm like me, and your motor will last forever, but dont forget the Amsoil
no drilling, no accusump, no coolers, 6 full seasons of racing.
by the way, when you do headers, pump up the fuel and vent the air box, its easy for a 928 5 liter engine to get 400crank hp. the GTS should make more, with the same set up and the GT Cams
Before you think that i have a special engine. i have stock 85 cams and a 5 liter bottom end that made 335 when it was kind of new (at least new to me) . One would think that was special, until a GT with the same set up on exhaust, made almost the exact same rear wheel HP. (and the curve's shape was identical)
so far, we have not seen a GTS race car with open exhaust and headers with the GT cams. got to imagine it would make 350hp without any fuss.
Until you see your HP curve, there is no way to think that 7200rpm shift points will do you any good. marks new engine (stroker 6.5L)
peaks at 500rwhp and it does this from 5000rpm to 6500rpm. You could shift from 6500rpm and not that be that far off, average power-wise compared to this engine shifted at 7200rpm. in fact, depending on how fast the HP falls, it could be a disadvantage.
AND, you dont have the special intake or all the porting work, but you do have the bigger valves which could help.
mk
no drilling, no accusump, no coolers, 6 full seasons of racing.
by the way, when you do headers, pump up the fuel and vent the air box, its easy for a 928 5 liter engine to get 400crank hp. the GTS should make more, with the same set up and the GT Cams
Before you think that i have a special engine. i have stock 85 cams and a 5 liter bottom end that made 335 when it was kind of new (at least new to me) . One would think that was special, until a GT with the same set up on exhaust, made almost the exact same rear wheel HP. (and the curve's shape was identical)
so far, we have not seen a GTS race car with open exhaust and headers with the GT cams. got to imagine it would make 350hp without any fuss.
Until you see your HP curve, there is no way to think that 7200rpm shift points will do you any good. marks new engine (stroker 6.5L)
peaks at 500rwhp and it does this from 5000rpm to 6500rpm. You could shift from 6500rpm and not that be that far off, average power-wise compared to this engine shifted at 7200rpm. in fact, depending on how fast the HP falls, it could be a disadvantage.
AND, you dont have the special intake or all the porting work, but you do have the bigger valves which could help.
mk