Base Line tune up

Ok guys I need a some imput here. I have a 500" Blown Hemi (Alky) We run this engine in a Mini Mod pulling tractor. I know, I know were not drag racers!! But I think that we have more in common with our engine setup than we do with our fellow grease burning tractor pullers So we have a new engine setup this year and were are trying to decided on going to a dyno or not to get our tune up right. Some belive that a dyno gets your fuel system all wacked compaired to actual passes down the track. We have a Racepac system to log all the engines vitals. So keeping an eye on things is not a problem. My questions are as follows
1) Whats your take on the dyno tune vs. actual track tunning
2) Our new setup should make better boost (cooler and more psi) I'm wondering how to guesstimate how much is enough extra fuel to through at it if we dont go to a dyno
3) What are some of your general exhaust temps that you feel are safe?

Not looking for trade secrets here just some basics. Thanks for the help?

 

Top Secret Information

Personally, if you have the finances and the dyno close enough to go to, I would suggest the dyno tuning. The main reason is that you may not be able to make enough laps in a reasonable amount of time starting out so fat to guarantee not to lean it out. You did not say roots or screw blower, though. Still, it looks like everyone's keeping their tune up suggestions TOP SECRET. Probably because it may be a Mission Impossible tape and the engine my self destruct in 5 seconds. You might be a little unhappy at the advise if that were to happen. Just my .02

 

Tune-up

If you have the money to set it up on a dyno, than by all means, but a true engine brake would be the best option if you can find one. Taking the dyno results, please remember that you need to add more fuel on the track since it will stay at high rpm / high power longer on the track than on the dyno and you will need to cool it. With the sled behind you the power output will increase to the end of the track whereas on the dyno you only have the acceleration run and no true 2500HP braking function at full rpm. It's only for a couple of seconds, but enough to smoke the engine with the dyno setup.
You can probably set up blowers and pro-chargers from some experience / estimates. These deliver a certain amount of air per revolution, so you can calculate / estimate what these would deliver. A turbo setup requires more effort and some luck as well, since you'll have to add some sort of boost-related injection.
A general rule of thumb seems to be 17 gpm with a 14-71 HH at 50% over, but there is no way knowing if that will work on your particular combination. Temperatures depend on heads, location of T/C, use of turbocharger (or not), so no way to predict without some information from a comparable setup. Lets say 1000F ?

 

It sounds like you have a workable setup and just want to add fuel for added boost? Is that correct? If so, how much more boost? What did you change to get this increase?

 

Sorry, I should have been more complete. We run a roots style blower (8-71). We have purchased a new blower. Our old blower had the smaller rotors and was from the mid '90 (approx). So how much new found air will we have? Your guess is as good as mine. We ran at 44% OD last season with boost numbers around 27-28 ish in the spring and mid to low 20's as the charger need rebuild. (We went way to long between blower rebuilds). Our new blower is a modern 8-71 design and is still being built so I don't have it installed yet. We are looking to push our setup harder this year, say 200-300 HP. Im well aware no one can tell me what Pills,injectors, ect to install just some gut feelings from you guys would be great. I'm sorta leaning towards the dyno tune right now. There's other places that $$$ could go but on the other hand I don't want to spend all season play'n super tuner when we should be reading track conditions. I really thank you guys for your words!

 

Add 1 gpm (at 8000), will take care of 300 HP. Pullers always need to consider fuel management to add some fuel down track.

 

Calculations??

So here I go showing my lack of knowledge but oh well! There must be a calculation based on fuel psi and pill size to figure the extra "1 gallon at 8,000" We ran a pretty mild tune before so we never had to add extra fuel at the end. What would method would recomend for adding the extra fuel towards the end of the track? Sorry for the dumb questions, but we need to learn to do this work for our self. I also should mention that we are limited to a single 110 fuel pump, so running dual pumps with different curves isn't an optioin.

 

Try this

http://fuelinjectionent.com/tuneup.htm

 

I've spent alot of time with Blown alky motors on Fred Mandoline's dyno. It will definately help you get your tune up to where you dont wreck it and show you what the motor likes and does not like. Fred does alot of dyno sessions for pulling guys. Mandoline Performance Development 630 782 0010

 

I talked with Fred last fall about some time on his dyno. I hope He has some time to help us out. Thanks again for everyone's help, both PM's and public info. I feel that we have gathered some new ideas to help the cause