How hard would 22 cubes cut grass? It's cut the slam heck out of it.
Adding 22 cubes,,, power increase? 528 to 550
- Thread starter gregsdart
- Start date
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Cert is 850. Block is a 2002 year mega block. It has been a lot of fun. Before the glass trunk lid and moving the battery to in front of the radiater it was a wheelstand monster. People would come to watch me run because it was a crap shoot what was going to happen.
Yeah, I foresee either cutting the tune back from maximum output or some chassis upgrades, lol!
When i moved all that weight forward the car settled way down. I expect it to work well with the extra power. I ran m5 alky for a while which is worth as much as 40 hp, chassis worked ok.
It’s also very probable the .4 point compression increase is going to raise your fuel demand too. More fuel is needed for evaporative cooling when increasing compression to keep chamber temps down under the 800 and some degree auto ignition point of methanol to prevent detonation. Detonation+Methanol= Melted Parts... There’s a point of diminishing returns of enrichment vs. evaporative cooling but your well shy of that. Good call from 273 on torque vs. rpm production. The hp production compared to race gas is usually the same at high rpm, but the methanol makes more torque across the power band until it gets there. The extra displacement will make big gains at low rpm's by the sheer force of cylinder pressure. The displacement increase is going to equate to probably around a 50 hp or so on top end based on displacement increase with an existing baseline between 850-900 hp (going by weight/e.t.). It could very well go past that mark too depending on how well cylinder heads and cam play along with everything. It’s the usual 35 plus percent torque increase that starts from the bottom and tapers off toward the end with methanol that makes the difference. The 4.30:1 gear is a good call, it may respond to tighter converter but it also may be somewhat tight to start with. You’ll know if it’s blowing through the converter if your e.t. & mph start to gap from what they should be. The combined changes should bring it very close (probably past) to that 8.50 chassis certification. The math shows the car is working pretty well at 8.77-153, compared to 1320/153=8.62 (98%!). Good luck with everything, I’m looking forward to how this one turns out.
Since my 60 fts are slow by .03 to .04 for my et, i agree there may be good cause to go to the 4.30 from 4.56. The data logger shows the launch rpm at exactly 6,000 rpm at launch/full stahl, and i have another converter that i believe to be about 400 rpm tighter. Shift point showed exactly 7350 rpm. The explanation of methanol torque versus gas tells me an alky combo will like a tighter converter?
I have some more shock testing to do also as the ladder bars are only 30 inch long and it looks like the Big Gun afcos may not be valved stiff enough.
Wyrmrider
Well-Known Member
22 cu inches great idea with the offset grind
Your heads are going to determine your top end hp and I would not count on much increase there however below peak torque should be greater as you can work the heads to the max at lower rpms
The jones inverse flank rollers run like 4-8 degrees larger than they spec
so otb i would make no changes
Did you have Mike run the numbers- I'd install it wherever he suggests
Theoritacally the extra compression, although minimal could suggest a wider lca but I'd not do anything till you run it and maybe move the cam around a little- whatever Mike suggests. rod ratio and crank throw also change requirements
it's complex- so run where you left off and go from there
Have you plotted your piston to valve at different timing (icl) with the new pistons
I'm sure you know this but with those asymetrical lobes timing of the max lift icl is useful only of you figure it out in relation to the seat timing you need to be timing from seat timing icl
cheers
Your heads are going to determine your top end hp and I would not count on much increase there however below peak torque should be greater as you can work the heads to the max at lower rpms
The jones inverse flank rollers run like 4-8 degrees larger than they spec
so otb i would make no changes
Did you have Mike run the numbers- I'd install it wherever he suggests
Theoritacally the extra compression, although minimal could suggest a wider lca but I'd not do anything till you run it and maybe move the cam around a little- whatever Mike suggests. rod ratio and crank throw also change requirements
it's complex- so run where you left off and go from there
Have you plotted your piston to valve at different timing (icl) with the new pistons
I'm sure you know this but with those asymetrical lobes timing of the max lift icl is useful only of you figure it out in relation to the seat timing you need to be timing from seat timing icl
cheers
Thanks for the info. I measured at different points on the first install but will go with .015 tappet lift and see what it looks like. Then ask questions.
Agreed on not changing anything on the cam timing, and the data logger is especially useful. I would probably run the tighter converter, too, if it's "blowing through the converter" now, it's going to be worse with the extra displacement and especially the longer stoke. Good job on the data logger! I imagine your monitoring individual exhaust Port gas temperatures to help with the fuel tuning?
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yellow rose
Overnight Sensation
Damn you need a 4 link. No way is a 30 inch anything ever going to correct. Even if you valve the shocks so it takes two cranes to pull them apart, that short, high IC is killer.
I'd bet everything I have your car with your power would want an IC 2-4 inches off the ground (who knows...if you have 50% or more on the rear axle you may need a 0 or even a minus IC height) and at least 108 inches out. Again, could be longer depending on weight distribution.
At your level 48% on the rear axle is miles better than 50%.
Bigger tune window with alky, so i run one temp sensor, check the plug bases for heat. I shoot for about half of the NGK plated plug bases to be scorched. That seems to be about right.
On the converter, slippage isn't out of line at about 8 percent. I will start with the loser one, for apples to apples comparison. Same with the rear gear since it hooked OK with the m5.
Duane
Well-Known Member
So when they apply this coating, it goes on uniform in thickness to not require any machining afterwards?
I am currently at 47 % on the rear with a 106 wheelbase. I know the 30 inchers are way too short, but I am below the neutral line at 5 1/2 inches off the ground. So, I am considering going to a fourlink but not right away.
The coatings wear in during the three cycles of warmup and cooldown bwfore you can put a load on them.
That’s a good approach, one change at a time. Easier to go back to redo.
Duane
Well-Known Member
So this was a way to do a rebuild with straight cylinders and re use the Pistons in a slightly bigger bore, good to know.
yellow rose
Overnight Sensation
Ok, 47% on the back is actually pretty good for your power to weight ratio. I'm a bit surprised you needed to move some weight forward. But, with your short IC I'm not surprised it helped...just a little surprised it needed it.
yellow rose
Overnight Sensation
You can use it for that, but you can also use it on a fresh engine. That's what I'm going to do.
What ends up happening is you end up with near zero running clearance, which makes the piston more stable in the bore, which increases ring seal.
Duane
Well-Known Member
How much clearance are we talking here. The trend with Pistons nowadays already is tighter than say 20 years ago. I bought new custom Ross Pistons uncoated and they recommend .004 clearance.
Can you put a number on it?
yellow rose
Overnight Sensation
IIRC, it's near zero running clearance. I'm going to call them again next week and verify that, but that's what I remember.
Edit: by near zero I mean .001 or a bit less IIRC.
Scares me to death, Lolol! My mindset is maybe just a little too archaic to want to try that for myself just yet.
Duane
Well-Known Member
That's tight wow. Thanks for the info.
Got a call from R & R in Spring Lake Park. Mn where my parts are. I had the heads CC'd again due to changing valve sizes, twice over the life of the heads. They were supposed to be 62cc when i bought them from Indy years ago. Now they are 67? I went from 2.19 intakes to 2.25, then later i went to a 2.30 intakes but to do it the exhaust got cut to 1.78 from 1.81 and was sunk a bit. The flow on the intakes went to 399 at .800 from 379 but i never saw any performance gain.
With a .100 flat dome about offsetting the valve pocket volume, i figure compression at .045 quench will be 15.01 to1. So i haven't ever had the compression i thought i did. I was figuring it on 62 cc not 67 that it is. But it all worked out for 550 cubes.
The block had some cap walk and alignment issues. I guess stuff moves around over a period of 18 years. I hope it doesn't take a lot to square that away. It will be a while before i am able to get working on this motor. Maybe mid May before it will make noise.
With a .100 flat dome about offsetting the valve pocket volume, i figure compression at .045 quench will be 15.01 to1. So i haven't ever had the compression i thought i did. I was figuring it on 62 cc not 67 that it is. But it all worked out for 550 cubes.
The block had some cap walk and alignment issues. I guess stuff moves around over a period of 18 years. I hope it doesn't take a lot to square that away. It will be a while before i am able to get working on this motor. Maybe mid May before it will make noise.
If your running into cap walk issues with a MegaBlock, your really putting some power down. I would go ahead and have new exhaust valve seats installed to get the exhaust valve back up to it's proper seat depth. You aren't going to get any more air and fuel into it if you can't get the exhaust to scavenge properly.
The cap walk issue isn't as bad as the first 100 passes. It was making great power and when torn down we found the new crank had a crack in it. Not serious, and it was ground out. I sold that crank and bought a Crower center counterweighted crank. I will ask about the exhaust hieght.
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