Let a new adventure begin... ITBs on a GTS lump with a twist...
11-09-2011, 05:51 PM
#1
Rennlist Member
Thread Starter
Let a new adventure begin... ITBs on a GTS lump with a twist...
Santa arrived early this year I guess...
trumpet arrangement should make for an interesting airbox arrangement
This little project of mine should answer an interesting question which has been posed on Rennlist about a thousand times - what happens when you ITB a standard displacement engine. The 50mm ITBs are going on a 5.6ltr dry-sumped GTS lump with 12:1 compression, Colin's cams, 928INTL headers into a custom X-pipe and 2.5" dual exhaust.
What horsepower do you think it would make?
trumpet arrangement should make for an interesting airbox arrangement
This little project of mine should answer an interesting question which has been posed on Rennlist about a thousand times - what happens when you ITB a standard displacement engine. The 50mm ITBs are going on a 5.6ltr dry-sumped GTS lump with 12:1 compression, Colin's cams, 928INTL headers into a custom X-pipe and 2.5" dual exhaust.
What horsepower do you think it would make?
Last edited by Cheburator; 11-09-2011 at 07:42 PM.
11-09-2011, 06:31 PM
#2
Are those the M5 snorkels?... Look very much like what ATB is putting together for his stroker motor..... You can position them facing inwards to reduce the size of the "air box". are you going to run the stock MAF..or something else?
11-09-2011, 06:51 PM
#3
Rennlist Member
Thread Starter
Yep, they are off an E39 m5. Initially was going to use E60 M5 throttle bodies, but then realised that the E39 ones have a much simpler linkage system, which would make mating them to the 928 heads a relative dodle. Will be using Alpha N with the LH/EZK via JDSs new black box of magic tricks. As with regards to the airbox arrangement - you are right - I would copy the BMW one and turn them inward as I quite like how it has dealt with limited space under the bonnet.
11-10-2011, 01:10 AM
#4
Rennlist Member
wiser and easier to lose the throttle bodies and just use the M5 plennum with all the "snorkels" inside. then you could do it with one or two throttle bodies.
why re invent the wheel, the best thing to ever hit the 928s was the later version of the CF intake like Fan and Anderson have!
why re invent the wheel, the best thing to ever hit the 928s was the later version of the CF intake like Fan and Anderson have!
11-10-2011, 04:24 AM
#5
Drifting
boy I have heard the carbon fiber tb of threshie fame were not able to be tuned easily and never ran correctly......is there some other cf intake made..
also I think john speake has put itb;s on his gts motor hasn't he??
also I think john speake has put itb;s on his gts motor hasn't he??
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11-10-2011, 04:57 AM
#8
Rennlist Member
How did you end up with a 5.6 litre engine? I presume you are running a GTS crank with slightly larger bore pistons? The 968 type pistons usually add about 0.5 litre?
If what I have followed over the years is anything to go by you shold expect to gain another 30 to 40 hp for the ITB's.
Guess it is all mixed in with the cams, sharktuning, headers etc. My prediction when sorted:close to 500 rwhp?
I'll SWAG it at 485 rwhp!
Regards
Fred
If what I have followed over the years is anything to go by you shold expect to gain another 30 to 40 hp for the ITB's.
Guess it is all mixed in with the cams, sharktuning, headers etc. My prediction when sorted:close to 500 rwhp?
I'll SWAG it at 485 rwhp!
Regards
Fred
11-10-2011, 08:45 AM
#9
Rennlist Member
Thread Starter
wiser and easier to lose the throttle bodies and just use the M5 plennum with all the "snorkels" inside. then you could do it with one or two throttle bodies.
why re invent the wheel, the best thing to ever hit the 928s was the later version of the CF intake like Fan and Anderson have!
why re invent the wheel, the best thing to ever hit the 928s was the later version of the CF intake like Fan and Anderson have!
1. Bodging the M5 airbox to mate to 928 heads with two throttle bodies is much more difficult than fitting ITBs with adaptos plates.
2. If the CF intake was so good, how come Louie and Mike S are using ITB... Hell, them people at BMW, AMG, GM, Porsche and Ford to name a few must be really dumb given that their race engines use ITBs...
How did you end up with a 5.6 litre engine? I presume you are running a GTS crank with slightly larger bore pistons? The 968 type pistons usually add about 0.5 litre?
If what I have followed over the years is anything to go by you shold expect to gain another 30 to 40 hp for the ITB's.
Guess it is all mixed in with the cams, sharktuning, headers etc. My prediction when sorted:close to 500 rwhp?
I'll SWAG it at 485 rwhp!
Regards
Fred
If what I have followed over the years is anything to go by you shold expect to gain another 30 to 40 hp for the ITB's.
Guess it is all mixed in with the cams, sharktuning, headers etc. My prediction when sorted:close to 500 rwhp?
I'll SWAG it at 485 rwhp!
Regards
Fred
11-10-2011, 09:28 AM
#10
Rennlist Member
Assuming you are going to work the heads to take advantage of the cams [bigger valves gas flowing etc?], the cams are roughly worth what the Devek B2 grind gives and looking at what Louie eeked out of his monster motor, working backwards suggests that you ought to be proportionate to 550 less capacity and stroke components- say 10% for stroke and 5% for bore?
Maybe I am too optimistic.
Best wishes
Fred
11-10-2011, 09:41 AM
#11
Three Wheelin'
wiser and easier to lose the throttle bodies and just use the M5 plennum with all the "snorkels" inside. then you could do it with one or two throttle bodies.
why re invent the wheel, the best thing to ever hit the 928s was the later version of the CF intake like Fan and Anderson have!
why re invent the wheel, the best thing to ever hit the 928s was the later version of the CF intake like Fan and Anderson have!
11-10-2011, 09:54 AM
#12
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11-10-2011, 11:16 AM
#14
Drifting
I am very curious to see how you mount those and handle the linkage. Do you intend to do the fab work yourself? Sharktuning or aftermarket engine management?
Why I keep my mouth shut when engine threads pop up... someone with some serious knowledge will come along and put me in my place!
Why I keep my mouth shut when engine threads pop up... someone with some serious knowledge will come along and put me in my place!
11-10-2011, 11:28 AM
#15
Rennlist Member
Thread Starter
You should call Mike Simard.
Honestly, if I lived in the US I would have gotten his ITB system as it is better than what I am concocting. Unfortunately, crap FX rates and 5% import duty and 20% Value Added Tax on the cost of the goods + import duty + shipping costs make Mike's product expensive for me.
The heads already have 968 intake valves in them and have been ported properly by a guy who does nothing but head porting.
I have access to a skilled machinist, who will CNC all the necessary parts for me on the cheap in Bulgaria. We will need 4 adapter plates and a new platform to mount the linkage between the throttle cable and the actuating rods for each bank of throttles in the middle. As for the actual throttle bodies - they are separate and the linkage between them already allows for them being spaced further apart. Lastly, will have to machine new solid pipes, which link the ITBs for vacuum, but overall, the project is not that bad from engineering/ machining perspective...
Honestly, if I lived in the US I would have gotten his ITB system as it is better than what I am concocting. Unfortunately, crap FX rates and 5% import duty and 20% Value Added Tax on the cost of the goods + import duty + shipping costs make Mike's product expensive for me.
Whatever it works out at I am sure it will be exciting. It will be interesting to see other predictions.
Assuming you are going to work the heads to take advantage of the cams [bigger valves gas flowing etc?], the cams are roughly worth what the Devek B2 grind gives and looking at what Louie eeked out of his monster motor, working backwards suggests that you ought to be proportionate to 550 less capacity and stroke components- say 10% for stroke and 5% for bore?
Maybe I am too optimistic.
Best wishes
Fred
Assuming you are going to work the heads to take advantage of the cams [bigger valves gas flowing etc?], the cams are roughly worth what the Devek B2 grind gives and looking at what Louie eeked out of his monster motor, working backwards suggests that you ought to be proportionate to 550 less capacity and stroke components- say 10% for stroke and 5% for bore?
Maybe I am too optimistic.
Best wishes
Fred
I have access to a skilled machinist, who will CNC all the necessary parts for me on the cheap in Bulgaria. We will need 4 adapter plates and a new platform to mount the linkage between the throttle cable and the actuating rods for each bank of throttles in the middle. As for the actual throttle bodies - they are separate and the linkage between them already allows for them being spaced further apart. Lastly, will have to machine new solid pipes, which link the ITBs for vacuum, but overall, the project is not that bad from engineering/ machining perspective...