A few things to note:
Previously I had 10 times varience side to side on the A/F ratio (difference of 2.0 side to side), both The Carb Shop and ATI reccomended that I reclock the carb hat to have it's inlet pointed straight forward. On a dual plane apparently this is the ticket because the A/F's were very close side to side on this dyno session (single plane intake manifolds mask the effect of loading different air bleeds differently).
Quick Specs:
468 BBC, D2-R intercooled blower, Canfield 310cc heads flow ~ 335@.550, Chevy L78 intake, 830 Holley by The Carb Shop, Comp 11-404 base blower cam (this is small as far as big block blower cams go): .547/.547 lift, 232/237 duration, 114 degree centerline installed @ 112 degrees, HEI set at 31 degrees total advance.
The engine made about 60 hp less than I had anticipated, but I shut off early at 5,500 rpm because of boost concerns (originally I expected to rev it to between 5,800 to 6,200 rpm depending on indicated manifold boost.
After the first pull with the 4.75" blower pulley it only made 11 psi @ 5,500, so that was swapped out for the 4.25" pulley (stock 7.65" ProCharger crankshaft pulley).
Questions:
1) How much boost is really ok for an intercooled pump gas engine.
2) Has anyone here swapped out the FoMoCo Powerstroke intercooler for the Gale Banks on a Ford PowerStroke, if so what were the results.
So, I'm thinking that with a 26" or 28" tall E.T. Street tire and 3.08 gears I should fairly well be able to thunder down the track, while only revving to ~ 5,400 rpm.
Location: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Re: New dyno, 710 tq, 702 hp (The Green Rocket)
The reason it "only" made 700 hp is because that is a pretty mild build. Should haul butt and last forever. I am looking forward to seeing it at Garden Grove when you get it done.
Very nice results. You could probably pick up some of that 60hp you "came up short" on by leaning the A/F out past the peak torque mark. Peak torque should be the richest A/F ratio, then it should enlean towards peak hp. From my experience, peak torque is usually made at around 12.1 A/F ratio mark, although every engine is slightly different it[s usually in that area +/- a couple tenth's of A/F.
Hard to say what the max boost is for an intercooled pump gas engine. Obviously it's all dependent on cylinder pressure and octane. Static compression, cam profile (duration/overlap/LSA), cylinder head material, combustion chamber efficiency, induction/fuel system, compresser efficiciency, intercooler efficiency, etc all play a role in how much boost it will take before detonation is a problem. Some guys can run well over 20 psi of boost w/o detonation, while others can only manage around 10-12 psi. I can't recall seeing too many centrifugal supercharged pumpgas street engines with much over 15 psi though.
Keep in mind though, that overly retarding the timing to counteract detonation has a significant effect on power. Ignition adavnce for forced induction engine's makes a huge difference. On an engine like your's, 1 or 2 degrees of advance could be as much as 35hp or so at peak. I don't know what ignition box you're using, but the programmable MSD Digital 7 would probably be worthwhile for you sicne you can fine tune the spark map with nearly as much accuaracy and granularity as with an aftermarket programmable engine management system (EFI).
Very impressive. It looks to me like you could get a lot more power out of this motor if you wanted. If you leave it like it is, it will probably last a long time.
How much does your car weigh and what kind of times do you plan on running?
Hell, I suppose that I'm really only making half the power that this engine is capable of, but durability and reliability are two of my goals - so nothing is really being pushed to the edge. Low 8.3:1 compression, slow blower speed, small camshaft, low engine rpms, mild gearing etc.
Monty, I hear you on the advance - but like everything else on this engine I feel more comfortable being conservative. There is no ignition box, this is just a straight HEI, properly curved, with a 50,000 volt coil.
This engine is slated to go in my El Camino, which will get suspension updates to help me 60' good at the track. My goal is simple: to make it a drive anywhere car with A/C and all the other comforts that I can drive to the drags, install slicks, run a super low 10 second e.t.'s, then change tires back and drive away. Hanging the front wheels in the air at launch would be a welcome bonus :) I have the trans set for automatic full throttle shifts at 5,000 rpm, it will still have plenty of torque going into the next gear, I will run it out in third to ~ ?, maybe 5,400 rpm.
Location: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Re: New dyno, 710 tq, 702 hp (The Green Rocket)
This engine is slated to go in my El Camino, which will get suspension updates to help me 60' good at the track. My goal is simple: to make it a drive anywhere car with A/C and all the other comforts that I can drive to the drags, install slicks, run a super low 10 second e.t.'s, then change tires back and drive away. Hanging the front wheels in the air at launch would be a welcome bonus :) I have the trans set for automatic full throttle shifts at 5,000 rpm, it will still have plenty of torque going into the next gear, I will run it out in third to ~ ?, maybe 5,400 rpm.
Thomas[/quote]
Sounds like a good plan to me. If you get a good 60' you might have a shot at a low 10. It should go 10 something non the less.
*Minor Update*
The boost loss through the intercooler and intercooler inlet/outlet plumbing (which has two 90 degree transitions) was only ~ 4 psi, not the 5.5 psi originally reported. Since I do not have a boost guage at the supercharger outlet I was merely comparing same rpm boost with and without intercooler. As it ends up, the dyno pull that indicated ~ 5.5 psi drop had slight belt slippage. Today, with a retensioned belt the peak manifold boost increased to 17.8 psi, torque went up, but I pretty much have a surpluss of torque already.
I know that some people will say that is a high psi drop, but I think it is still respectable considering that it includes the intercooler, and all the inlet/outlet plumbing.
Thomas
[Modified by The Green Rocket, 12:20 AM 1/18/2003]
[quote]
I know that some people will say that is a high psi drop, but I think it is still respectable considering that it includes the intercooler, and all the inlet/outlet plumbing.
[quote]
That is alot of pressure drop though, less than 1 psi is ideal. If you're satisfied with the results, it's not a problem though. But I guess you always know you can pick up a little more power by improving the efficiency of the induction side of the system .
18psi on a carb'd pump gas street engine w/o detonation is pretty good, that means the compressor is actually making about 22psi in reality if your assumptions are correct. What is your s/c rated at?
Monty, if you say that is excessive I believe it, but like you said it can be a future area of improvement.
Do you have pressure and temperature guages mounted at the outlet of your turbos and then again in the intake manifold? I'm curious what you actually recorded on your engine.
Actually, I would be more interested in learning how it is possible to reduce air temperature from ~ 330 degrees to ~ 130 degrees and not have a significant volume change, with volume having an important relationship to pressure.
ProCharger offers the following rating on the D2-R model:
2800 cfm of max flow
34 psi max boost
53,000 max impeller rpm
At 5,500 engine rpm X 1.8 drive ratio X 4.44 internal step up = 43,956 actual impeller rpm.
In many ways this is a dream of an engine to tune: everything done to "fix" a probelm will resulty in more power :)
I have a datalogging system, but have not installed it in the car yet. It will measure the pressures and temperatures pre- and post- turbo. The only data I have so far is the IAT's. For a basic Spearco cored air/air intercooler rated at 1000hp/1500cfm, it has been pretty effective at keeping the IAT's down. Even under the worst conditions, like in an enclosed dyno room, my IAT's never exceeded 126F. That's with no air flow over the intercooler except for a small floor fan in the room.
I measure manifold pressure via the MAP sensor that the FAST SEFI uses, and I compared that to a boost guage connected right to the compressor nozzle. So this allowed my to compare boost produced right at the turbo vs. actual intake manifold pressure, indicating th efficiency of the entire induction system. The pressure difference varied from .2 psi up to .6 psi at WOT. The intercooler core itself was rated at .4 psi at 1500cfm, so my ducting must be taking another .2 psi at most. The key probably being that there aren't any sharp turns or bends.
With regards to you question about temp and volume. The volume is limited by the capacity of the induction system. As the compressed charge passes throught the intercooler and cools, it become denser since it can't expand in the rigid intercooler and ducting. I don't know if you've seen some of the turbo kits being shown on the C5 Forced Induction section, but some of them are using wire reinforced flexible tubing to connect the turbos to the intercooler and then to the throttle body. Even with the wire reinforcing, I can't help but think that there is some expansion. I would think this would even contribute slightly to lag - sorta how rubber brake lines give you a softer pedal feel compare to a hard or s.s. braided hose.
You're not even pushing that compressor that hard. Do you have a compressor map for it. At 44K rpm, you might not even be peaked out on efficiency, that's usually around 90% or so of max rpm. You've got alot of room to grow if you later decide you ned more power. There could be as much as 100 more hp with sometweaking of your current system, but as you say, it should be very reliable at it's current state of tune.
Monty, for sure I am very interested in hearing about your data logger results.
My goals value reliability over max power, you are right about my combo having a lot of room to grow. Actually, I want to first work on getting the chassis dialed in before I begin to think about more power. Once it can run consistent clean low low 10 second passes without any drama, maybe then I will start turning up the wick.
I do not have a compressor map.
If you were setting this up, what tuning or changes would you try?
Actually, I'd probably leave it where it is. Maybe you have more experience driving overpowered cars than I do, but I've found they can be a real handful. As you get accustomed to it, you could swap pulleys to spin the compressor a little faster, add a degree or too of timing and maybe lean it out a tenth at a time. You'll probably want to take it to the track to quantify your changes. I plan to do so myself this spring. I'm only shooting for low 10's myself.
Even the current power level will require finesse until the chassis gets all dialed in. More power at this point would only serve to beter entertain track spectators.
More than the horsepower, it is the massive low end torgue that is the tricky part of a mega power street mill.
Monty, your 1,200 hp/1,000 tq is enough raw power to runs 8's at 160 mph, 10 flats will be easy as pie for you. The one big issue is how to modulate the torque to keep from overpowering the tires at any point down the track. I actually expect that getting my chassis dialed in for quick short times will be the easy part - keeping it glued to the track on the top end will be the challenge.
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New dyno, 710 tq, 702 hp
