FrontEngineDragsters.Org Forum
Technical => Roo Man's Room => Topic started by: beargeorge on September 17, 2015, 05:32:13 PM
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Front engine dragster, 180 inch w.b. BB Chev.powerglide long or short? M.W. modular rear,my question is how far out should the motorplate be from the rearend centerline. This is a new build
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My car is 193" and the motor is out 39", the lenth of a full glide where one uses 1 set of couplers. Only issue is that motor and trans come out as a single unit, but they payback is less cost and no driveline slop.
Others will get into dynamics and front end weight of different setups , but is all a load of crap, every car -engine combo - track and type of racing we do can have a different sweet spot for optimum performance and honestly anything can be tuned to get down the track.
For me personaly I try to refrain from getting the engine too far out, gets the engine more centered between the wheels so the engine bounces up and down if you bang it with the transbrake going into stage so weight transfer gets confused because the engine is in motion. I like hanging weight on the front as it makes the car try and drive underneath the front thus helps plant the rear tires. If you are not running a PRO (non-index ) class it does not make any difference, one just makes enough HP to run under the index and adjust accordingly to hit the number.
I have a customer that was all scientific about engine location on his A/F car. Spent a ruddy fortune on tires, gear ratios, trans and converters and racing all kinds of tracks, still cant get it to stop shaking
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Thanks Bruce for your help.
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Our car has the engine placement in the same location as Bruce's car with a SBC and full length PG and coupler. It is a 223" car, probably 1700 # wet with driver. Certified to 6.0
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Thanks for your reply,nice car
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So Bruce you prefer a long glide with short coupler over a short glide with a coupler shaft that is like 18" long? The reason I ask is my fed has a shorty glide and I need a long coupler. Would possibly be cheaper to change to a long glide with short coupler? The engine in my car is out 42". I like the less slop statement...
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I'm 190 inch and 40 inches out. Long glide short coupler. 1630 lbs with big ol me and 40 lbs. lead on the nose.
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Sorry that I am late to the party but we were racing at BG over the weekend and I am just catching up on what happened while we were gone.
I agree with Bruce that you can make anything work for index racing. I normally put the motor about 42" out but even with it there Mark Vaught's car (225") needs some ballast in the nose to make it work. Frank and Scott would just build another car with the motor further out to fix that but they are running in a class where added weight is a "penalty". If you are running on an index, what the car weighs does not matter unless you are severely short on power (hard to do in this day and age). Ballast can also be a quick fix for other combination problems. If the car tries to rotate too hard at the step and hammers the wheelie bar you can help it with a bit more weight up front. A couple of our competitors this past weekend battled shake throughout the event with "motor out" cars running on what was a tight track. It is a little easier to add ballast than move the motor/change the converter/change tires etc.
Roo
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So Bruce you prefer a long glide with short coupler over a short glide with a coupler shaft that is like 18" long? The reason I ask is my fed has a shorty glide and I need a long coupler. Would possibly be cheaper to change to a long glide with short coupler? The engine in my car is out 42". I like the less slop statement...
I did mine for simplesity and cost as the cost of the long shaft in the trans was minimal verses buying an extra set of couplers and shaft (which is also extra weight and rotational weight) and building a driveline cover whereas my coupler cover is just a short tube mounted to the pinion carrier.
With all that extra driveline components and you leave off the trans brake, everything behind the trans has to make contact before the car moves. Jack the back of the car up while idling and apply the trans brake and rotate the tires by hand back and forth and be amazed at the slop.
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Thanks Bruce for the info last night on the phone and for all the help here. It is great to have everyone here to bounce things off of. Thanks to everyone...