[tom s]

I just can’t get a grip on how parts from one cyc can make it to so many others!I dropped one valve on the highway in one cyc and found shrapnel in almost all of them?Tom

[Scott Roberts]

Originally Posted by mgarblik

Well, it's been a week since Norwalk and in the interest of full disclosure, I have some info from our engine tear down. On our engine that ran the big MPH, we did have some engine chaos right at the finish line as you know if you were there. Some data from the run from the computer. At the traps, 8900 RPM's, 41 lbs. boost, 90% nitromethane fuel. 8 EGT's grouped within 50 degrees the entire run.
Damage report: #1 piston failed first. Fuel trapped around top ring land exploded and blew the top of the piston off. Similar situation for #3, but not as severe. When a piston explodes, not a melted hole, it sends pieces of piston everywhere in the engine banging and chewing up everything it gets into. So pieces of #1 and 3 pistons were found in 6 different cylinders. Heads have not been taken apart yet but some damage from flying piston pieces and some bent valves from crap getting caught between the seat and valve faces. With 450 lb. seat pressure it's a bent valve anytime this happens. Looks like the heads can probably be brought back to life without welding. One exhaust rocker arm has the adjuster smashed and the push rod tip mauled from junk in the seats as well.
Now for some good news. All rod bearings perfect. All main bearings good. We had to run regular street main bearings because -.030 bearings are not available from anyone in a race series. All main studs stayed tight and the block looks perfect. May need to replace 1 sleeve, not sure. For a 250 MPH run, worth it and not much different than what we see in the hemi stuff at every race we attend. So I guess we are doing OK. I will post some pics in a week or so. Need to clean the parts up.

You guys have taken on a huge task running nitro... there are no free lunches in that world..none! Congrats on the record and the relatively minimal damage! It's amazing you are doing what you are with a wedge head and nitro to be honest... not that you guys are not capable, it's just a tall order for anyone!! job well done to all involved!

[Scott Roberts]

Originally Posted by tom s

I just can’t get a grip on how parts from one cyc can make it to so many others!I dropped one valve on the highway in one cyc and found shrapnel in almost all of them?Tom

Welcome to the world of highly volatile fuel and high h.p.....

[tom s]

Mine neither!Pump gas 400 on the highway at 65 MPH!Tom

[mgarblik]

Originally Posted by Scott Roberts

Welcome to the world of highly volatile fuel and high h.p.....

There is a reason everyone running nitro uses a Chrysler hemi. The design is made for nitro. Huge, smooth chamber to keep self-ignition to a minimum, spark plugs high and centered, out of the liquid fuel, thick pistons in a block with very long cylinders. All these features really help the hemi live on nitro. However, I have seen plenty of hemi aluminum coleslaw. So you still have to know what you are doing. The Pontiac on nitro has a very narrow tuning window. We are running different compression heights in various cylinders to help tune for this. We are very close to having a great, high HP tune-up. To be honest, at these HP levels, nitrous, blown alcohol, you name it, they are all on the edge. Our oiling system woes, cost us allot of really good parts and 4 years we could have spent tuning. Now that we have that truly fixed, most of our good parts are pretty beat up. It's an unfortunate situation for a low buck team. We will patch up what we have and be racing again in 3 weeks. Funny Car Chaos in MI. We have to qualify and go 4 rounds. So, reliability will be required.

[Scott Roberts]

Originally Posted by mgarblik

There is a reason everyone running nitro uses a Chrysler hemi. The design is made for nitro. Huge, smooth chamber to keep self-ignition to a minimum, spark plugs high and centered, out of the liquid fuel, thick pistons in a block with very long cylinders. All these features really help the hemi live on nitro. However, I have seen plenty of hemi aluminum coleslaw. So you still have to know what you are doing. The Pontiac on nitro has a very narrow tuning window. We are running different compression heights in various cylinders to help tune for this. We are very close to having a great, high HP tune-up. To be honest, at these HP levels, nitrous, blown alcohol, you name it, they are all on the edge. Our oiling system woes, cost us allot of really good parts and 4 years we could have spent tuning. Now that we have that truly fixed, most of our good parts are pretty beat up. It's an unfortunate situation for a low buck team. We will patch up what we have and be racing again in 3 weeks. Funny Car Chaos in MI. We have to qualify and go 4 rounds. So, reliability will be required.

Different compression heights to tune cylinder.... I talked to Frank Manzo about that exact deal... he told me he ran different compression in cylinders for tuning and fuel distribution... you guys got it covered! I would love to come see you run... might have to make a road trip...

[Jack Gifford]

Thanks for sharing Mike!
Is there such a thing as a "conservative" tune for you guys wanting to go four rounds?
Does the other engine look good?

[mgarblik]

Originally Posted by Jack Gifford

Thanks for sharing Mike!
Is there such a thing as a "conservative" tune for you guys wanting to go four rounds?
Does the other engine look good?

Well, sort of. Engine seems to run the 1/8th mile with much greater reliability. Next race is an 1/8th mile event. They seem to be more and more popular. We may need to look into dropping our gear ratio from 4.11 to 3.89 which is the next stop. Now that we are making more power, 8900 RPM is pretty high. Also we have gears for the fuel pump to increase the fuel volume some more. We are just about out of tuning range with the current fuel volume. Losing several years of tuning time chasing oiling system problems has really hurt us. That seems to be way in the past now thankfully. Changing a few pistons and running a ball hone through a cylinder is super easy compared to having to line hone the block, have the crankshaft ground or replaced, and other major damage from oiling issues. Slowly, we are getting a handle on this. The other engine, I will look at this week. If it passes a leakage test, we will go with it as is. If not, I will open it up as needed. Spark plugs didn't indicate anything unusual. We ran it pretty fat to protect it.

[Steve Barcak]

Originally Posted by mgarblik

Well, sort of. Engine seems to run the 1/8th mile with much greater reliability. Next race is an 1/8th mile event. They seem to be more and more popular. We may need to look into dropping our gear ratio from 4.11 to 3.89 which is the next stop. Now that we are making more power, 8900 RPM is pretty high. Also we have gears for the fuel pump to increase the fuel volume some more. We are just about out of tuning range with the current fuel volume. Losing several years of tuning time chasing oiling system problems has really hurt us. That seems to be way in the past now thankfully. Changing a few pistons and running a ball hone through a cylinder is super easy compared to having to line hone the block, have the crankshaft ground or replaced, and other major damage from oiling issues. Slowly, we are getting a handle on this. The other engine, I will look at this week. If it passes a leakage test, we will go with it as is. If not, I will open it up as needed. Spark plugs didn't indicate anything unusual. We ran it pretty fat to protect it.

Mike- glad to see you plan on changing the gear- it seems much to steep to me for this app. you will get the MPH easier ( if the easy should apply ) with the taller gear. Even a 3.90 gear seems a little short to me but, you obviously know what you are doing. Not sure what comparable 426 cars are using for gear with that size tire but, you may want to look into that and align accordingly. Nitro loves load so, a taller gear should benefit. If you need more launch, a gear change in the trans may be the ticket but, again, am sure you know what you are doing. I always ran my car without a trans because that was the rules in my class. They now allow a low gear so, I bought a 2 speed to bolt to my reverser to use one day.

How nice to have the exhaust temps all aligned like that. That is about impossible to do with a conventional Pontiac/small chev port arrangement. Glad the V and the M/T HEMI Pontiac have 4 separate exh ports ( KRE does too ). that is a blessing for a nitro burner.

Yeah, the different compression heights, etc has been around for decades but, is only mainly know in the nitro ranks ( I think ) so, most Pontiac guys outside of nitro, would not be familiar with it. I was working on that with my AA/Fueler 15 years back.

Am glad your bottom end is fine, that must be a great relief. Not sure where your issues came from. I had a few little bottom end issues when I started but, got on top of them and they went away. Most of my issues were in the head castings.

Am surprised you are so conservative on your percentage. There is a LOT more power avail as you up the mag and percentage. Sounds a lot better too! Are you going to try more percentage? I started with 90% thinking that was too much but, when I tipped the can to 92, it responded well. It did better each time I brought it up and went as high as 97% but, was running 95-96% before I had to park it. It loved the extra percentage and great header flames!
as long as parts are living, why not? Lots of power by 'tipping the can' and 'turning the mag'
take care and congrats again.
Nothing is better than a blown Poncho on nitro!

[mgarblik]

Thanks for chiming in Steve. The 4.11 gear ratio was chosen at the get go, when like you we were running the car direct drive. As heavy as it is and with the big tire diameter, it worked OK. Now with the 2-speed and the car making more power, a change may be in the future. The 9.5" ring and pinion are a big expense and it's allot of work to change. Nitro %, I kind of leave with the tuning experts. Bill Miller is a big proponent of "pick a % and make the engine run properly on it" Then increase the % but expect to more of less be starting over at every 3% change.". With our limited ability to get laps on the car, we just haven't been able to experiment much with nitro %. Your really spot-on about magneto though. Our car just loves as much lead as you dare to run in it. Once while tuning it after a rebuild it started with 70 degrees of lead in it. It sounded just incredible. We had just under 60 degrees in it on our best run. Take care.