With the timing locked I have run 25 , 26 , 28 , 30 , 31 , 33 & 34 . at 25 it is soft everywhere and as I give it more timing it goes quicker. but note that more timing will pick the 60 ft up much more than 330 or 660 . if say the 60 picks up .06 the 330 may only pick up .04 and the 660 maybe .03 , so while the ET is quicker the top end HP is less and retarding the timing does nothing to help this. looking at the valve spring issue , I now think that maybe advancing the timing picks up the HP which in turn raises the stall speed and the RPM at any given point on the track and puts it above say 6500 sooner ( which it doesnt seem to like ) so the HP down track is less , for more time !!! did that make sense ???
Cylinder Pressures @ 40 LBS of Boost?
- Thread starter BlownV6
- Start date
Yes, makes sense. Well I dunno about your blown alcy motor, but a stout S2 heads mill on race gas and say 25 psi of turbo boost would prolly want no more than your minimum 25 deg timing setting there 
I'm sure it would want much, much less on 40 psi...
Effect of the alcohol fuel on timing- sorry, I have no experience there...
TurboTR
I'm sure it would want much, much less on 40 psi...Effect of the alcohol fuel on timing- sorry, I have no experience there...
TurboTR
Real quick like....you may not be able to use anything other than an aluminum rod. Reason being, the shock absorbing quality of the rod. You may be stuck with a situation were you have to "drive thru" a certain amount of detonation and a steel rod won't tolerate that. IMO
If you have to keep the .999 60 ft times.....that means keeping the timing locked and everything the way it is. That also means that when you crack the throttle the cylinder pressure is at an insane level until you can get the rpm up and it settles down hopefully with better valve springs this time
Dale
If you have to keep the .999 60 ft times.....that means keeping the timing locked and everything the way it is. That also means that when you crack the throttle the cylinder pressure is at an insane level until you can get the rpm up and it settles down hopefully with better valve springs this time
Dale
QuickWrench
Don't Read This
- Joined
- Jan 28, 2002
Any word on the new springs? I'm interested to give some feedback, but things are likely to change drastically once you've gotten things properly set up. I'd guess that if you try throwing 30+ degrees at it on the tall end of the run, you're going to have problems, once all of that boost is being fired correctly.
Get good springs in there, back it down some, make a couple of hits, and see where it's at. Then we'll kick it in the ass.
Get good springs in there, back it down some, make a couple of hits, and see where it's at. Then we'll kick it in the ass.
Sorry guys we just got back from vacation. Valve springs are going to be used Manley #221449 ( got 4 sets ) set up around 430 to 450# on the intake seat . I got new Isky red zone lifters that are for late model Bow-tie blocks .350" taller than standard Buick lifter , which in turn makes the push rod .350" shorter . going to use 7/16 - .125 wall pushrods at about 7.750" long to handle the load. this should put the valve train under control !! Also looking at how to get the fuel pressure more in line with the boost !! Looks like detonation during the burnout , the hit of the throttle and the shift are all real possibilites !! still looking !!!
Dave Flanders
New Member
- Joined
- Jan 11, 2004
I've been trying to follow the progress on your combo for a while now and wanted to thank you for pushing me to think more about valve spring pressures. I do have one thought to throw out for your problem...
What type of ignition? If you're trying to fire all that fuel volume with an HVC coil and MSD CD box (anything short of a 10+) you might be mistaking lack of power at higher revs with a lack of ability to burn the fuel. Plus the fact that running even a teeny bit lean to compensate will lead to detonation.
Your combination is far removed from mine (turbo alcohol) but I eventually learned that with enough spark you don't need excessive timing to make it run. I used to look at the blown hemis with their 40 psi/40 deg. of timing as a benchmark but your small chambers shouldn't need that much.
Maybe one more thing to think about? Those blown alky V8 guys must be switching to a 44 amp Pro Mag for a reason?
Half Fast Racing
What type of ignition? If you're trying to fire all that fuel volume with an HVC coil and MSD CD box (anything short of a 10+) you might be mistaking lack of power at higher revs with a lack of ability to burn the fuel. Plus the fact that running even a teeny bit lean to compensate will lead to detonation.
Your combination is far removed from mine (turbo alcohol) but I eventually learned that with enough spark you don't need excessive timing to make it run. I used to look at the blown hemis with their 40 psi/40 deg. of timing as a benchmark but your small chambers shouldn't need that much.
Maybe one more thing to think about? Those blown alky V8 guys must be switching to a 44 amp Pro Mag for a reason?
Half Fast Racing
Point taken and long ago did look into ignition. I use a MSD digital 7 with the 2 amp HVC coil. this is according to MSD as close to a 44 amp mag as is available . 44a mag is not available for 6 cylinders. we do have a belt driven 44a mag figured out but this thing shows no signs of ignition problems. all exhaust temps stay lit. more fuel may bring this issue to a head but were not there yet. thanks
Mike,
This board is very good and has some of the top guys post herehttp://www.promodifieds.com/ Good luck,Scott
This board is very good and has some of the top guys post herehttp://www.promodifieds.com/ Good luck,Scott
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