110mm bore 928 engine project - plans for a 7.4 liter in the works.
04-05-2006, 03:32 PM
#61
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Cool, thanks for the pics Tim! So now that means I'm going straight home after work to start on my my car.
04-05-2006, 03:32 PM
#62
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Jim,
I was going to bring that engine up this morning to draw some conclusions but I came to the conclusion that not enough was known about it. I was particularly suprised by how low an RPM the massive torque was made. I think peak torque was made by 2,000 RPM. In looking at the engine I would suggest the intake system was designed for torque. I think it had very long intake runners. The only important unknown would be the cams that were being used. Given the lack and cost of aftermarket camshafts they were probably standard S4. Anyway my conclusion is that the car probably did not make a tremendous amount of horsepower given how low in the RPM range the torque was made. To maximize HP I would bet it could use more cam, larger valves and port size.
I was going to bring that engine up this morning to draw some conclusions but I came to the conclusion that not enough was known about it. I was particularly suprised by how low an RPM the massive torque was made. I think peak torque was made by 2,000 RPM. In looking at the engine I would suggest the intake system was designed for torque. I think it had very long intake runners. The only important unknown would be the cams that were being used. Given the lack and cost of aftermarket camshafts they were probably standard S4. Anyway my conclusion is that the car probably did not make a tremendous amount of horsepower given how low in the RPM range the torque was made. To maximize HP I would bet it could use more cam, larger valves and port size.
04-05-2006, 03:35 PM
#63
Originally Posted by Tim Murphy
Don't forget the 2" diameter hollow drive shaft.
04-05-2006, 03:47 PM
#64
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Hope he has a seriously upgraded water pump: if the cylinder water volume is reduced 90% or so, he must have a hell of a lot of flow to offset the heat exchange rate. Incredible project though!
04-05-2006, 04:25 PM
#68
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Originally Posted by Hacker-Pschorr
Who said everything behind the motor was stock? 
His skills are not just limited to engines.
His skills are not just limited to engines.
Just out of curiosity, what is it ??
This has been a hurdle for a lot of people for a long time.
04-05-2006, 04:37 PM
#70
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As mentioned first he runs an automatic which greatly reduces the potential for abuse(Bill Ball excluded) second his purpose is NOT 1/4 mile drag racing and it seems he has upgraded the driveshaft. A lot of people have dreams.."Quite the project! What dreams are made of.." in this case however he simply quietly makes it a reality . I really admire that.
04-05-2006, 04:38 PM
#71
Three Wheelin'
Originally Posted by Barry Johnson
Holy crap, thats awesome... Someone asked if the S4 would flow enough for that bore, and IIRC, an S4 head can't hold valves large enough for really much above 6l. I'm sure Sensei Louie would know :^)
I spent some time playing with Engine Analyzer Pro checking out the effects of putting S4 heads and intake on a 7.4L bottom end, then seeing the change with a Vortech S/C, then with 968 intake valves, big cams, and headers. One thing I noticed was that at 6000 rpm and 10 psi boost, the S/C take 74 hp to drive. Don't take these calculated values as gospel for the numbers the actual engine will produce, but they do show the effect of different changes.
The top chart shows a 7.4L bottom end with stock S4 heads, valves, cams, and exhaust. Then the same setup but adding a Vortech S/C with 10 psi @ 6000. The bottom chart is with the S4 heads and S/C compared to using 968 intake valves, Devek B1 cams, and header exhaust. The top end is improved a lot. More gain can come from even better breathing. If the heads could support larger valves and ports, larger intake manifold passages, and anything else to improve breathing the gains continue to rise at the expense of some low end torque. Changing to a 4" diameter throttle body is good for about 30 lb ft of torque and about 10 hp.
https://rennlist.com/forums/attachme...d=109366&stc=1
74_2.jpg
https://rennlist.com/forums/attachme...d=109367&stc=1
74_3.jpg
Last edited by Louie928; 03-18-2008 at 01:12 PM.
04-05-2006, 04:55 PM
#72
Todd was very very happy with his (compared to this) puny little 5.0L with the 951 pistons. He shot the 25psi we heard about through that engine. Every time I talk to him he waxes poetic about that combination. A bit weak on the low end he said, but it really was fun up top.
04-05-2006, 05:21 PM
#73
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Originally Posted by MarkRobinson
Hope he has a seriously upgraded water pump: if the cylinder water volume is reduced 90% or so, he must have a hell of a lot of flow to offset the heat exchange rate. Incredible project though!
04-05-2006, 05:58 PM
#75
Originally Posted by tv
Thats the other engine program they have.
This 110mm bore engine design Todd has will start with stock crank and rods. It will be about 6L as I recall him saying. It will probably grow when he learns more from this, but yes, this new sleeved engine is stock crank and rods.
That other is the 6.1s they built - yeah, I just checked - thats the one with the outside cylinder support rings. Thats what Todd has in the car as of today, and the last year or so I believe.