Finishing the racecar blog. Yes?

[Henson]

1) More static compression means more off-boost power and better throttle response. Since he's got more than enough power with the blower, the engine is built for more basic non-boosted grunt.

2) If you didn't measure the static compression ratio, then you really have no idea where the engine is. You will have lots of fun making all kinds of WAG estimates during the upcoming tuning years. it's much easier to measure stuff before it's assembled and installed into the chassis. Get to work.

3) Single word? Fail. The gapless rings are a bad idea. Plain and simple. Take them out now before you wear out the engine and have to do it all over again.

Let's talk about current turbo engine design, CR and boost levels at the reunion. I expect you will be quite surprised what stock engines are doing now.

1) I wonder what is better… upping the compression on a four cylinder turbo race car 12.5% or deleting the long front mount intercooler? Hmm, throttle response? What do you think the HP gain is from 8 to 9 on a NA engine?
2) Yea thanks Mike. Where were you 8 years ago?
3) That's Cool. At the time Essy said No problem. I gritted my teeth as I rolled out the dice.

[Horsewidower]

Henson, a couple of thoughts. Remember that I'm running the racecar on e-85, if I was starting over with that as the fuel I'd run at least 10:1 at the limited power numbers I'm allowed to make. The turbo is there to fill in low rpm torque. I'll probably be making the numbers at less than 12 lbs of boost. If I ran the ARCA head it might run at single digits. If I ran in the unlimited HP/TQ class I'd probably drop the CR to the 8:1 and run at a higher rpm. If I was running it NA the CR would be in the 13.5 to 14 range. The difference in power NA between 8 to 9 isn't worth talking about, and you would clearly run much higher CRs. I personally prefer your choice in charge cooling for the exact reason you state. We'll see how we do. I wouldn't be increasing the CR without some effective charge cooling.

It wouldn't be too hard to get a reasonably accurate CR for your engine, if its in the state you showed in the picture. Your piston manufacturer probably lists what the -cc is for the piston and you can get the head cc'd. Then check whether or not the piston is in the hole, zero decked, or out of the hole. You probably can check an old head gasket for its installed thickness. Then with a little math, you'll have a decent figure.

8 years ago, gapless rings were the hot thing. I think that trend has passed. But you don't seem to have had a problem, so unless you intend to breath on it heavily, or change your tuning and driving habits, carry on. Scope creep may start to set in if you pull the engine all the way down.

[fitzmotor]

The valves are just Ferrea custom peices, it is so I can fit in my big block Chevrolet beehive springs.....how stupid does that sound??...very.
But this killer camshaft (no joke, shreds valvetrain) requires a really high frequency spring, thats is where the BB Chev spring comes in, ever try to fit a 1.880 spring into a Pinto head? even with .150 higher keeper groove I will still have to cut the spring seat .200, if it works, I should be able to hold this thing together.
I tried Ti retainers and 170lbs seat pressure/450lbs open springs....this f#(K!ng cam put a hurting to them in 80 miles, but I wont give up on this cam, it drives like a large displacement NA motor (no lag) not optium for max power, but great for roadracing in a HP restricted class.

So, if all goes well tomorrow doing the final machining on the head, I am looking like I have more of a chance for Nov @ BW, this is not about the bet, its about my determination to run in American Iron.

But the bet still stands, next year when everybody is ready we can resume the challenge.

[Horsewidower]

You got enough beef in that head to take a .200 cut? Did you get the springs from PAC or Comp? So you're at about 2640 wet? Man, you gotta be killing them under braking. And you can push the crap out of them and thier tires are going to get greasy.

The AI guys are up here this weekend. Wish I was there.

[fitzmotor]

Esslinger says that .200 is the max, I hope that's right, otherwise I am screwed. The springs are from Pac, an ovate wire, polished, nitrited beehive.
I am at just under 2600 lbs now, I will have to make some adjustments, adding ballast will likly be it.

And yes the tire/brakes thing is what lets me run with the higher HP cars, until something fails.

[Horsewidower]

Wow, 2600 with you in the car. I need to lose some weight. I assume the valves are longer? Isn't that going to reduce your lift?

Its the "something fails" that's driving us nuts.

[fitzmotor]

Ha.....Hmm.....sadly No, that is without my a$$ in it, my minimim race weight this time without ballast should be about 2780 lbs, I am the one who needs to go on a diet.

Yes only .025 longer, but the keeper groove is .150 higher, I did lose .020 lift, but the geometry was not optium, now it is, besides .570 lift is enough.
The head machining is done, if it passes the pressure test I am good to go.

Touching on the static compression subject, if you have a chamber that is knock tolerant, higher is better, but it really comes down to the fuel, at peak cyl pressure (combustion) the given fuel has a definate knock threshold (based on cyl press more than timing)
So, on pump gas you would be better off with lower CR and more timing, on race fuel/methanol you can have higher CR and timing before reaching the threshold. Now the chamber is the one variable to this, we actually found that shape,(both chamber and piston dish) quench and texture or coating have a huge effect. For example coating the piston and the chamber produced more knock (despite magazine articles) as the piston/chamber could not dissapate some of the combustion heat, pushing the fuel knock threshold lower, but heat is energy, so you dont want to lose too much of it into the head/piston, (not a problem with a iron head) but it became a trade off, keeping the energy in the cyl produced more power, but having to lower the timing actually left us with less power than a uncoated engine.
Quench/squish is also important to knock, the knock tolerance of engine with a zero deck piston with a .080 head gasket would be worse than one with a .020 gasket.
There are many variables, atomization, temp and how much oil is in the chamber,(oil is a fuel) we use cyl pressure sensors to measure knock magnatude (not on MY eng, the ones at my work) when properly tuned for max power it will have low magnatude knock that you cant hear, or will cause any damage.
After all this typing I doubt I have really informed anybody of anything, bottom line is, the specific engine designers have optimized the CR for the given application on pump gas, 2.3T at 8.0 to 1 others like Subaru's/Evo's 10.0 to 1

[Horsewidower]

Fitz: Thanks for that information!! Man, running piston to head clearance down to .020 is awesome, no stretch in those rods eh. What do you think the best CR is for the D port aluminum head?

I thought AI weighed with driver, so you have a 292 hp ceiling. Right?

Bob

[fitzmotor]

The torque is what I end up having to set my weight to, it's like 268hp/292tq @2800lbs.
I am only going with 8.3 CR, this car likes lots of timing, and I am running a street map with pump gas and 2 alky secondary injectors, then a track map with race fuel and alky.
I am not running .020 squish, that was just a example, I ended up at .051 I wanted it closer but, oh well, I was in a hurry.

[Henson]

Bob- You’re the Man. Who am I to say anything?
I must have forgotten about the E85. It would be nice to sit down and talk to ya some day. I would like to hear what you think about my set up and more importantly expectations and do some future planning for me. Yea! That would be great You, Mike, Fitz, Pat, 86, Raven, Monkey, Rinner and whoever else Mod’s their motor; sit down and discuss what I should do to make big reliable Horsepower. That would be Great!

Yea I can easily get the piston data. I kept all that stuff. No Problem I just have to look it up. I think they were Crower. I remember they were $100 each! Back then it was a big deal. Oh, that was a Picture from mid Last year.

Well I guess I was a sucker on the Gapless. Mike is going to brake down for me this weekend.

[Horsewidower]

Henson I'm just here to help. You oughta try to get out here when we run at Buttonwillow. You'd get the vast majority of those guys, I'm sure. Why don't you start an engine thread and we'll all help out.

Fitz, I know its sort of giving advice against my own interest, but you can go up to 311 torque at that weight. Torque is a 9 lbs per number, not 9.5. Run it at 2628 lbs. 268*9.5= 2489, 292*9=2628. You're giving up 8 hp, but I'm not sure that its worth chasing. Perhaps a bigger AR on the turbine housing, but it'll move everything up the rpm range, and I know you like that stump pulling torque.
Sorry, made a mental leap on the squish.

[Raven855]

Refresh my memory, is it just peak torque or is it peak and average?

[Horsewidower]

Just peak.

[Horsewidower]

We have a longblock, I went over and put that together.

We're trying to decide whether or not to see if we can get the existing engine to run long enough to find the electrical problem that we think we have or just go ahead and throw the new engine in. I'm going to drain the oil and cut open the oil filter on the existing engine and see how bad its gone. IF not too bad, then I'll fire it and see if I can find the glitch. If not, we'll take our chances with the new engine. This'll be engine change # 6 or 7 this year. I'm getting way to good at this.

[Horsewidower]

Good point Mike, but, the oil cooler is integral with the radiator. ??