hello. i see from the threads here that you do alot of turbo testing. wondering if/what you've done with turbonetics 6665 bb...not sure what their part number is, but Cotton's sells it as a cpt66. i've got one installed with my new combo. feels like it spools pretty quick, decent pull up top, although i couldn't fully lay into as i had trans issues. wondering what kind of power i can expect at 23-25 psi, 93 and alky.
Question for Bison
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With a mystery cam and ported iron heads I made 600whp@28psi on one combo. The engines CR was under 8:1. I don't recall what it made at 25psi or less. Probably 560. With a purpose built 9:1 engine it will make 650whp@27psi. I ran the gtq version and made 687whp@24psi on a different engine with better heads and 9.3:1 CR. That turbo is one of the best values out there. I've seen them new for less than $1000. It's a low 10 sec turbo
I used really good converters to get these numbers. I think that car had a 16 blade PTC 9.5". Id guess it was less than 18% drive train loss. Definitely over 650 flywheel based on fuel consumption.
NICE!! i'm trying a new converter from a guy local to me.. PA.. Transmission Specialties... they do alot of serious race convereters over this way.. i'm going to be using a 10" lock up unit with oversized composite clutch, billet cover and plate..supposedly a pretty serious piece.. stalls at 2800 @ 0 psi, 3200 @ 1-2 psi... not sure of how many blades, etc., but holding up to alot of abuse by Buick guys around here..
You will need to run it locked to get it to couple under power most likely. With a 212/212 and good heads you need it to flash to 5100 to really get it done. What ive found is that its easy t oget a converter to work on one end or the other but getting them to work on both ends is tough.
so, are you saying lock it out of the hole (2nd gear)? or, flash to 5100 out of the hole, then lock it up top? or neither or?? i'm a little leary of locking in 2nd...blew up 2 Pat's converters that way once i was under 11.50... but they weren't oversized lockup clutches either...
If you cant lock at WOT reliably then you should consider a non lock up converter if you are looking to get the most out of a combo. A non lockup like i run takes full advantage of the whole track. You get the coupling power of the converter in all gears. Not just after its locked up like a lockup converter.
Dusty Bradford
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This "oversized" clutch may have a little more surface area than a standard clutch but it won't be much difference. Only way to get enough surface area in a 10" converter is to add multiple clutches. 3-5 disc. Then you have over $1000 in a converter that still won't spool like a non lock and has to be locked at WOT to couple efficiently.
you guys now have me wondering if i made a mistake in buying a lockup converter. i do mostly street driving with the car. a few trips to the track, and anything that wants to go for a rip on the streets. what's the slip % difference between lock and non lock units? what are we talking in terms of e.t/ mph difference?
Dusty Bradford
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It all comes down to the rpm vs hp of the combo. I have lock-up converters that slip 6% and some that slip 18%. Once the slip gets excessive with a lock-up, swapping to a non lock can drop it in half or more. 14-18% slip can be dropped to 6% easily.
The hp vs rpm is what we have to look at here. It's possible for a 5200 rpm stock cam engine running 11.20 to have more slip than a combo that turns 6000 rpm and runs 10.80. I can take a converter that slips excessively at 10.50 and 5600 rpm, then put it behind a 7000 rpm LS1 and run 9.60's with it. RPM capability will increase efficiency.
So there is no cut and dry answer here. Slip% difference and converter requirements depend on the combo and hp generated. If your not taxing the converter you currently have there can be little to gain.
"RPM capability will increase efficiency." So, do you mean max rpm that a given combo will make power at, or the engines ability to reach a certain rpm in a certain amount of time? Or neither? Seems like a hell of alot of information to need to know before getting a converter.
If you raise rpm via larger cam and other supporting parts the coupling will be better with a given converter. You are trading off cylinder pressure at lower rpm. If you have high cylinder pressure you get the opposite. If you have one car with 800wtq@4500rpm and one with 650@6400rpm the second one even though its making more hp will not drive over the converter like the first one. The first one would be out of breath before the converter could couple if it was built for a higher rpm/hp application. The more typical "street" builds have high cylinder pressure and lower peak torque and work the converters a lot harder. You need to have the right company build your converter for what you are running. If you take the converters in my cars for example you would not produce the best times at lower boost levels because the coupling ability is so great. It will hold the engine down below peak power which does not translate into the fastest et
Dusty Bradford
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I'm talking shift rpm. A converter works off of centrifugal force, more rpm = more coupling. So if a car makes enough power to run 10.80's and shifts at 5300 rpm the converter will be less efficient than a car that runs the same et but shifts at 5800. This is why it's important to match a cars shift rpm with the cam size. You want the engine to operate in the proper rpm range.
Pronto
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What would determine the best shift point if you have a new engine? The cam/heads?
Dusty Bradford
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Cam and valvetrain.
From what I have seen and Bison can probably go even further with his extensive dyno testing.
A 231-234 with a 212 cam will pull to 6000 rpm. It will run the best et when you keep the rpm in a window, lets say 5200-6000 rpm. A 218 or 224 is way to big. A 218 will pull to over 6700 and a 224 will pull past 7000. Therefore if you have a 231-234ci engine with a 224 cam, you are over cammed and the engine is not operating in it's ideal window being shifted at 5800.
This also applies to someone with a 212 cam who lets the car shift automatically at 5300-5400 rpm. It's all about the details. If you have a 212 cam and the trans is shifting early you need to get the trans fixed to shift at the proper rpm or shift it manually.
That's what I've found but it has a lot to do with mass flow through the engine. Typically a 212 duration cam will peak around 5200 with a p trim turbine run for all it's worth and will start laying down over 5800. A 218 will peak around 5500 and carry it over 6000 depending on the turbine and compressor. If you have a 71hpq with a fast ramp 218 cam it will make power to 6300 no problem. The compressor needs to be run hard for it to be worth going that high. If you have a TSM engine that peaks at 5700rpm and is still within 4% of peak at 6300 it won't be the same if you turned it way down to low 20's boost. The shift rpm will actually be lower. Most of the time I've found it to be best if the converter flashes to within 100-200 rpm of peak power. Once it does this half the battle is over. You just need to have enough of everything else to make it down the quarter. I've noticed shifting the 1-2 or 2-3 at a lower rpm than the car crosses the traps at will usually make it go quicker. It's takes a lot of power to get that much rpm in 3rd. When in doubt shifting early seems to be better than late if the converter flash stall is correct. Most on here with a 212 cam have no reason to shift later than 5600. If they have a car capable of trapping more than 130mph then there may be some benefit.
Pronto
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Good info! I have found that short shifting has netted better ets. I figured it was b/c of keeping a high load on the engine.
Bison, not trying to correct or proofread you, but i'm confused. you said above "the second one even though it's making more hp" but the figures are 800 and 650, respectively. But my real question in response to all the replies is..... and i'll put in terms that i understand, don't know all the proper terms for converter parts...so, the outside of the converter, which is spinning with the engine, spins the inside of the converter, which spins the transmission. So, when the transmission shifts, the engine (outside part of converter) slows down, while the inside is still spinning faster.? so "rpm vs. hp ability".... the ability for the engine(outside part of converter) to catch back up with the inside??? sorry this sounds so stupid, and i appreciate all of the replies...
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