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Discussion Starter #1 (Edited)
I'm just now getting my junk together, and I was wondering what your opinion was on my converter.

I have a 367" iron headed blow through small block mopar. S475 (96mm 1.32 cheap version), non-intercooled on E85. Cam is real small, 224/218 .500"/.500" on a 114LSA (in at 111 ICL) 9.2:1 comp. Heads are ported iron, flow ~250/180cfm or so.

Anyway... enough about the combo...

Dyno'd the car last fall, carb wouldn't richen up enough so we were down in the 10~11psi range. Converter flashed to 5200, slipped to 18%, and made 470rwhp @5400rpm.

Called PTC and they told me that the dyno can load the converter strange and not give it a chance to lock up. They said to try it in the car on the road.

Fast forward to this week, and I got the car out. 10psi again, can't get it to hook in 1st gear, but in 2nd it just flashed up to 5200 again and stays there.

Sounds like it's waaaay to loose to me. PTC wasn't convinced, and took some convincing that it should be sent in?

With peak HP at 5400, I can't possibly see why 5200 flash at 10psi is a good idea. I'd like to get this heavy(3650lbs) small tire (255/60 drag radial) pig into the low tens, so I assume I'm going to have to throw quite a bit more boost at it.

This is a 9.5" PTC. I have a MSD boost controller, MSD digital 6 ignitionr, and a trans brake. I'm hoping I can have them tigten it up a bunch, and still get it to spool on the 2/3-step/brake?

What do you guys think? Where should this thing stall at? I'm assuming it'll take 600rwhp to get this thing to 10.00, so maybe 18psi?
 

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My mustang in my avatar is similar weight and rwhp.....also logged 18+% slippage.......poor mph but went [email protected]
about 10.3x 1/4..

The hp #'s will come up when that slippage is fixed....it's toooooo loose for shure
 

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Chupa Cabra
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Can u rev it more?

Bit hard to blame a converter, when the mis match parts make it difficult...
Yes it does. I think he should also spin it more and see if it tightens with RPM.

If PTC thought it was going to make peak torque around 4800-5200rpm and peak power at 6300-6500 like that cam should then it's going to be loose until you spin it up where it was spec'd to make peak power.

The part that still makes me think that it might be the converter though is you said it won't go any higher than 5400rpm. How long did you hold it WOT while it was staying at 5400rpm?
 

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Like i told you last fall. Id be changing the cam before id change the converter.
 

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Discussion Starter #6
Well it doesn't have the worlds best short block, so I was trying to keep the HP peak RPM down with the small cam. I am SURE it would make more power wound up with the big cam, but I just didn't know if the short block would handle it. I was sort of surprised that it only made peak HP at 5400 though. I would have thought that cam would have made peak a little higher.

It may slip less with more RPM, but it won't fix the flash stall problem right? I think we pulled it to 5600~5800 or something, but it was falling off already past 5400.

BTW... which parts are mis-matched? Small heads/small cam/ mid sized engine/ small turbo... I thought it sort of all should play together well?

Not blaming PTC for anything either, it wasn't my point to bash them. They are willing to fix it for sure, so I am happy with that.

LilJohn I really hate to change the cam in this thing without even running it. 3.23 gear with 255/60 radials at 130mph and 8% converter slip would put the trap RPM right at 5600 or so... right in the ball park for the peak HP I'm seeing right now.

Thanks for the input guys, keep it coming.
 

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Well you know how i feel about that reverse split camshaft...

And with a head that doesnt flow well... Id have a touch bigger stick. Bigger cam would also soften up the bottom end a touch and the converter might not seem so loose. Yer making damn good torque down low with the small head, static comp and fuel. Being on that small tire and trying to make this thing hook and run that low in the rpm band will be a challenge.
 

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Discussion Starter #8
What do you think it should have for cam in it? Can't get much more lift then .500" because the stock lifter bodies are only good for spring pressures in the ~350lbs range, which is what I set the springs up to at .500" lift.
 

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I think you put a 10inch converter in it. last we talked you could get the motor to go 5200 on the tbrake.thats useless
 

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If this is a 9.5...the $900 converter..... it can be tightened and will spool better than anything else out there for it's low flash stall rating. Tell them to tighten it 600 rpm. If it don't spool well it won't be the converters fault.........it's a very low rev'ing combo you have put together. If you could spin it 5800 it would be a whole new world.
 

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Why didn't you spin it higher? Sounds to me like you saw the converter flashing a little higher than you had expected and kinda gave up without doing further testing. Do you have pictures of your dyno graph?

Here's a dyno graph I have. This was with a 61mm compressor with a p-trim turbine and a smaller cam. Sure, peak HP appears to be even less than 5400rpm, however all the way up to about 6000rpm the power doesn't fall off much at ~10psi. Maybe 30-40 horsepower there, but it isn't like it plummeted. I'd imagine yours would look more favorable between peak and 6000rpm? In which case why not spin it even higher than that to see what happens?

This is 360 cubes (stock magnum engine). 1.92 valved mopar r/t heads untouched (flowed about 210cfm on a flowbench). 210/222 .530/.519 113 cam.

 

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If this is a 9.5...the $900 converter..... it can be tightened and will spool better than anything else out there for it's low flash stall rating. Tell them to tighten it 600 rpm. If it don't spool well it won't be the converters fault.........it's a very low rev'ing combo you have put together. If you could spin it 5800 it would be a whole new world.
This is right on and liljohn is as well.
As I recommended way back you need more cam to make HP with that combo but if I were in your shoes I'd try it out and see where I stood before changing a thing. Have you got the dyno sheets to post?
 

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Discussion Starter #13 (Edited)
Well my goal was to try and keep the RPM under 6k. It's got a stock block, stock rods (with good bolts), stock cast crank, off the shelf probe pistons. Not exactly bullet proof... Just trying to keep the RPM down so it will live. I am sort of surprised that it made peak so low though. The cam is even in at 111 ICL, so it's not exactly set up for low grunt. Here is the one dyno graph I have, the bottom is in MPH but you can see the speed is REALLY low for a 26" tire and a 3.23 gear. Peak HP is ~5400rpm on this run, so we must have pulled it to 5800 or so?



2012-06-16_08-11-06_294 by wright2305, on Flickr

Sorry for the shitty picture, but you can see that the peak HP drops off a lot. The top speed in MPH at the far right of the graph was only 112mph. Obviously not locking up the converter. 6% slip, 3.23 gear, 26" [email protected] should only be 4900 RPM.


It doesn't sound like it's breaking up or anything, here is a dyno vid of it too. Only pulled to 100mph on this vid, but you can see it just flashes and stays there... (fast forward to 1m18s to skip the BS)

BTW... don't mind the whacky A/F ratios on this pull, the connector plug was loose.

http://www.youtube.com/watch?v=GJSSX6hqo6M


I guess the bottom line is that it could probably use more RPM, but if the converter already flashes to 5200 at low boost, it will run right over the peak RPM once I turn up the wick. I don't see much sense in trying it how it is right now. Maybe this winter it can get a bigger cam if the car won't run the number.
 

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I guess the bottom line is that it could probably use more RPM, but if the converter already flashes to 5200 at low boost, it will run right over the peak RPM once I turn up the wick. I don't see much sense in trying it how it is right now. Maybe this winter it can get a bigger cam if the car won't run the number.
I still think this is the problem. You need hard data to base your claims on. Have you taken it to the track as-is? Do you know how it behaves with 18psi? Speculation is only going to get you so far...
 

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What PTC was telling you is that dyno slip % can be innacurate because of how the converter is loaded. If you put the car in high gear and wack the throttle at 3000 rpm for example the converter may flash to a higher rpm than it would at the track when launching in 1st gear. That is why they suggested taking it out on the track or street to see how it does. Roll into the gas in low or 2nd gear, run it up to 5600 rpm or so and shift it to see if it still drops to 5200 rpm. If it does, we know the flash stall at that boost level is 5200 rpm. They would then know to tighten it 400-600 rpm and hope it spools for you.
 

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If this is a 9.5...the $900 converter..... it can be tightened and will spool better than anything else out there for it's low flash stall rating. Tell them to tighten it 600 rpm. If it don't spool well it won't be the converters fault.........it's a very low rev'ing combo you have put together. If you could spin it 5800 it would be a whole new world.

X 2

I've got the same converter . And its 7% at the top end .

Drives like a stock converter . Spools great on the street .
 

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Discussion Starter #17
The roll bar isn't in the car yet, so I can't run it at the track. But rolling into it in 2nd and making the shift to 3rd drops to 5200 and stays there. Goes to 5200 on the trans brake too at that boost. It doesn't have enough traction in 1st to see where it will flash in 1st. Might be lower, but too hard to tell.

No doubt increase in torque will increase stall speed though. Maybe I'm making a mistake, but I got the converter out today. Sending it back Monday to get tightened up. While it's gone I'm hoping to work on the roll bar so when it comes back I can make some hits.
 

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The roll bar isn't in the car yet, so I can't run it at the track. But rolling into it in 2nd and making the shift to 3rd drops to 5200 and stays there. Goes to 5200 on the trans brake too at that boost. It doesn't have enough traction in 1st to see where it will flash in 1st. Might be lower, but too hard to tell.

No doubt increase in torque will increase stall speed though. Maybe I'm making a mistake, but I got the converter out today. Sending it back Monday to get tightened up. While it's gone I'm hoping to work on the roll bar so when it comes back I can make some hits.
I agree. Sometimes it's hard to test on the street with tire spin.

What boost do you plan to run it up to?

I'm sure 5600-5800 will be easily doable with that combo. Your in the same boat we are in with the Buick V6's but they can reliably turn 5600-5800 with stock crank, rods and pistons at over 500rwhp.

If your current flash is 5200. 600 rpm tigher would take it down to 4600 rpm and allow room for more hp. Shifting at 5400-5600 should make it work ok for you.

I personally prefer to raise the shift rpm so spool-up isn't sacrificed so much. Tighten it 400 and shift at 5800 but that's just me. If spool-up isn't all that fast now, 600 rpm will knock it in the head.
 

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The roll bar isn't in the car yet, so I can't run it at the track. But rolling into it in 2nd and making the shift to 3rd drops to 5200 and stays there. Goes to 5200 on the trans brake too at that boost. It doesn't have enough traction in 1st to see where it will flash in 1st. Might be lower, but too hard to tell.

No doubt increase in torque will increase stall speed though. Maybe I'm making a mistake, but I got the converter out today. Sending it back Monday to get tightened up. While it's gone I'm hoping to work on the roll bar so when it comes back I can make some hits.
needs a different stator, you did the right thing. Maybe rpm will follow the cam better with a proper stator in the converter. I'd bet it picks up, but having a converter that can go 5200 on the brake when peak hp is 200rpm away is useless. if the converter comes in earlier, maybe the hp peak will move up some to.hard to say with slip that bad.

and the dyno doesn't fuck with the converter.and its not like there isn't piles of data to compare to that correlates to the basic fact that, that converter was way to loose.

adding more boost would just make the situation worse. With the current boost level the converter needs to flash to around 4400 tops, needs to foot brake to 3200 and be able to make 4-6psi of boost on the tbrake and hole 4400. your way shy of that, and given the 26 inch tire, I'd prefer to see you nueter some more.
 

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Discussion Starter #20
I think we'll end up running max 18psi on the combo. I think the turbo will be close to all done on a 370" motor without an intercooler at that point on E85 blow through. Depends on how good it hooks, but ultimately I'd like to see one 9.99 pass in it's life. Might take 18psi to get it done at 3650lbs and minimum traction. We'll see...

I know in N/A form this motor could live to 550hp crank 6500~6800RPM all day long. But in order to keep the same combo live at bigger power I'm trying to limit it to 6,000 max. Might have some more room for error in there, but I'd rather not test it if I don't have to. The short block is cheap...if I run it over later trying to push it, that's one thing. But running it over within the first 10 passes would piss me off.

I'm thinking if they can hit it in the 4400~4600 area, shift at 5800, should be close to what it needs. I have a new set of 255/60 drag radials for the car too. They are 27" so it'll help the hook a little more then the 26 x 10.5" ET streets.
 
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