New to E85. Few questions

[KevinB]

Thanks Lonnie, that's is right on. I am going to slip in a new tc this week to see what it does before pulling entire drive train. It should be a tighter version of the loosest tc i have used yet.

The ptc's all spooled real fast but my engine doesn't have the power to overcome the big drops in rpm....remember, i have a 234" so I might not have the low end torque a stroker does. Even with the juice, it still can't do anything at 5200 rpm. It feels like my old 125 two stroke dirt bike when it falls out of the power band. Tuning wise, I tried everything, probably why it is wounded. But even when this engine was in my old car, I never really ran more than 21 degrees of timing and leaner than 11.1 on c16. Probably one reason I've never hurt the engine or blown a head basket....also I never had a converter that dropped more than 800 rpm. The ptc', no matter if I shift at 6700 or 6200 or 6000, it always droops to 5100-5200. This summer has been great...I have learned more than i ever have about making power with my car. 100+ runs all with data logs and many different setups has been interesting. I pretty much run this car on average 6 times a week. Hell, I might have more than 100 runs now that I think of it. The cheap gas has really helped me accomplish this...because I am not able to spend a lot of money on my racing program. This year has been worse than others for whatever reason.

 

[Phoneguy]

Hi Bryan,
When Kevin installed the first converter we thought the converter was just too tight. When he installed your converter we found out its just the PTC converter. Both converters acted exactly the same with yours being a little looser than the first one. I have never used a PTC or even tuned a car with one. Its so much different than what I expected. I will try to make this short but explain. Kevins car has widow where it makes power roughly from 5500-6500. Give or take. First thing we noticed is when converter was installed on paper the numbers look great and spool up is excellent. Slip in the 5% range steep rpm shift drops. So far so good. One problem we could not figure out was why his car actually slowed down. Old converter slipped 20% car ran 10.20s with less boost!!!!!!! no way this car could have slowed down with a converter that looks so good on paper. Thats what we were thinking. After many passes we see what the issues are. Old converter had torque multiplication car would 60ft 1.5s or better 10psi and 3800 rpm on 2 step. New converter 20psi and 4500 on 2 step car is still sluggish and 330s are way down next to no torque multiplication. Old converter shifted 6500 and drops to 5800 right in sweet spot but still no efficiency for top of track. New converter no matter where its shifted it likes 5100-5200. He shifts 6800 drops to 5200. 4800-5200 is major danger zone for detonation. New converter shift drops are into danger zone and rattles engine on 2-3 shift drop. Too keep from blowing the heads off car we needed to pull timing. (I have no idea how you could keep heads on a car with this type of converter) Pulled timing car slows down again. Add 100 shot of the juice same problem. Car wont 60ft wont 330. We set the car on explode it still wont run to the 330. To answer the question the converter loads the car so heavily on the shift drops that we needed to pull timing to keep from blowing it up. Nothing wrong with the converter it spools fast and has good efficiency numbers. I just dont think its the right converter for this type of combo.

Lonnie, thanks for the explanation. When I ran my car in NC my tranny was only shifting at 5600-5800 and the rpm drop was about 500, if I ever get my motor back together it will be interesting to see what happens when it is shifted at 6500. Will it drop back to the same ? I sent Kevin a couple of XFI logs from my car at NC, have you looked at them? My car was running pump and ALKY and was running pretty fat @ 10.0 a/f , couldn't hold any boost at the line. With a 0 psi launch my 60' was 1.64, 330 was 4.485, 1/8 mile 6.912 @ 101.28, timing was 21* boost was 22psi. Full weight GN with AC.

Bryan

 

[Dusty Bradford]

It's real simple, my 9.5 PTC is too tight for Kevin's combo. It's dropping 1600 rpm because of the shift point and hp level. If his engine likes 5600-6500 then I need to loosen it a good 600 rpm and it will go faster. It will be looser on top and on bottom, the bottom will help the 60'. A converter that slips 20% will always 60' great on a car with the power level most of the V6's run at because the rpm is so high for a given boost level. But they give that up on the top end of the track. When this 9.5 is right it works on both ends. The cars launching at higer rpm aren't 60' footing on horespower, they are doing it with rpm so it's not torque multiplication we are talking here. It's just like launching a clutch car at 3000 rpm vs 4000 rpm. Once the converter is dropping the proper rpm at the gear change the launch can be fine tuned. As it stands right now, it's just too tight.

 

[Dusty Bradford]

Just to add to this. A converter should always drop back to the same rpm at a given power level. It doesn't matter if you shift at 5800 or 6800. If it drops to 5200 rpm at 26psi it will drop to 5200 no matter what you shift at. This is what's called your flash stall. Then when you go to 32psi it may only drop back to 5400. As you increase torque to an engine it raises the flash stall. This is why a converter has to be spec'd for the hp level and rpm range it will operate at.

 

[Phoneguy]

Dusty, is 5200 what my converter is spec'd at for flash?

Bryan

 

[Dusty Bradford]

Dusty, is 5200 what my converter is spec'd at for flash?

Bryan

It's spec'd for your rpm range and hp level. It's really hard to pin down an exact flash stall because of so many variables including engine torque curve, converter pressure, tune...etc. That's the purpose for the free restall policy. It's spec'd as close as it can be to a certain combo and then it's track tested at the power level the car will be raced at. If it doesn't stall where needed to benefit the car then I restall it to make it right. In your car and Kevin's it's flashing to the same rpm which shows your making similar power but his higher shift point and operating range needs a higher flash stall of a looser converter. Once he gets the engine to stay in the proper rpm range and drops slip from 20% to 10% there will be gains.

 

[Dusty Bradford]

Kevin. Post up your timeslip data if you have it from the runs with Phoneguy's converter vs the other loose converter. Include some info like boost level and ambient air temp.

 

[KevinB]

Kevin. Post up your timeslip data if you have it from the runs with Phoneguy's converter vs the other loose converter. Include some info like boost level and ambient air temp.

I will do that later tonigh when I get home.

 

[Dusty Bradford]

OK. I'm real sure it's just an issue of the flash stall being too low for your engine combo. The engine is most likely laying too low in the rpm range as the converter couples causing the 330 to be off.

Tuning wise, This flat spot in the rpm curve is where you want to apply more power if it's available. If the rpm flat spot doesn't shorten then the converter is obviously too tight. I'm not familiar with E85 but knock even with excessive rpm drop has never been an issue on C16. Our TSM motor drops 1200 on the gear change, My small block dropped 1400 and liked it. That's one reason I'm nervous to push a car with E85...it's still pump gas and scares me.

 

[KevinB]

OK. I'm real sure it's just an issue of the flash stall being too low for your engine combo. The engine is most likely laying too low in the rpm range as the converter couples causing the 330 to be off.

Tuning wise, This flat spot in the rpm curve is where you want to apply more power if it's available. If the rpm flat spot doesn't shorten then the converter is obviously too tight. I'm not familiar with E85 but knock even with excessive rpm drop has never been an issue on C16. Our TSM motor drops 1200 on the gear change, My small block dropped 1400 and liked it. That's one reason I'm nervous to push a car with E85...it's still pump gas and scares me.

I am not at home but I can tell you that if I launch at 4500 rpm, you can see the rpm dip 500 rpms right off the tbrake release. If I launch the car anywhere below 4000, it takes it about 100' to start moving. It just bogs down bad. If a tc was loosened up high and down low at the sametime, my spool up would be instant. I will try to get all the info from everything tonight.
first tc was an old art carr that was the best so far. Unfortunately it broke second time out. Next tc was an edge that was super loose. After that was one from jasjamz which was a ptc. That was tighter then the current tc from bryan. So, you can imagine all the info I got.
I am going to pull the engine tomorrow and figure out why its down on power. Hoping its just a head gasket any rings and I can get it up and running in a week.

 

[Dusty Bradford]

It would loosen down low and up top so yes spool-up will be instant. That's the benefit of having an engine shifting at 6500. I can raise the flash stall which makes spool-up even easier. I have several cars who drop only 600-700 and slip is still around 8%. It's odd the flash stall is as low as it is with your combo considering the part# you have but it's most likely just due to the converter pressure the trans is making...which isn't a bad thing.

 

[KevinB]

Here is the run down:
(if you ewant the dfi data logs, I can email them, the software is free from accel)

Last weeks (Bryan's ptc, 80 degrees, 30 psi with roughly 100 shot of n2o right off tbrake release.) 10.5x28 slick

1.563 60' (no tire spin, 2 step at 4500)
4.366 330'
6.62 660' 108.44 mph
8.56 1000'
10.202 1/4 137.75
2-3 shift 6640 drop to 5410
5900 through traps

BPG ths finals (bryans ptc, no nitrous, 30 psi, 90+ heat) 10.5x28 slick
1.607 60' (no tire spin, 4500 2 step)
4.39 330'
6.67 660' 106.14 mph
8.66 1000'
10.346 1/4 133.78
2-3 shift 6430 drop to 5350
5750 through trap

Norwalk semi finals (28 psi, 80's temp, loose edge converter) (can't find finals atm) on 275/60 hoosier dr's
1.50 60'
4.29 330'
6.65 330' 104.2 mph
8.67 1000'
10.31 1/4 129.7
2-3 shift 6430-5780
6300 through traps

The norwalk info......I didn't get a data log in the finals, but I turned it up to 32 psi and it went 10.2 @ 132 mph. I can't find the timeslip either, which would have been the best indicator but it did go 6500 rpm's. Unfortunately I removed that tc after this race. Looking back I wish I would have stuck with it one more time out. Car had a couple 1.45 60's this day also

Earlier this spring year(art carr, 80's temp. 27 psi) 275 radials
1.70 60 (tire spin)
4.43 330'
6.69 660' 108.97
8.64 1000'
10.30 1/4 134.69

2-3 6010-5600
6270 traps
This run was when car was first put together. I short shifted 2-3. I think engine may have been in better shape possible too. Thought car was going to fly at this point in the year, hell a 1.7 60' and a 10.30, would have thought a 1.5 60' would have been close to a 10.0, then 3 more psi would have been easy 9's.

 

[KevinB]

For reference, this is one of the last good passes in my old car. Same exact engine and tune, 70gtq (which on paper should be equal to the 6768 I have now), 100lbs lighter, th400, 275/60 dr's, 70's temp., bradco converter

1.47 60'
4.02 330'
6.19 660' 112.57
9.715 1/4 137.08

2-3 6350-5910
6610 through traps

pretty much same tune, same exact engine, different turbo, 30 psi

Seems like the engine needs to stay close in rpm drops. On paper this converter don't look good, but it got the job done.

I sold the car to a friend with this converter and he will not sell the tc or car back

 

[rmar]

I sold the car to a friend with this converter and he will not sell the tc or car back

Midnight auto supply can get it.......:biggrin:


Just wanted to say, Great thread Kevin. Thanks for taking the time to post your findings. Alot of good info.

 

[jasjamz]

So, have you found any downsides to the E85?
Should have my engine back in two weeks and the OD back next weekend.

 

[Dusty Bradford]

Good info. It does look like the engine likes staying in the upper rpm range. Do you think the motor was hurt from the 10.20 pass to the 10.34 pass? Just wondering why it lost 4mph when everything with the tune stayed the same. It picked up 8 mph from the edge and ran equal mph to the TSM car so it just needs to 60' better and you should be where you need to be. Keeping the rpm up higher should be all it needs.

 

[KevinB]

Good info. It does look like the engine likes staying in the upper rpm range. Do you think the motor was hurt from the 10.20 pass to the 10.34 pass? Just wondering why it lost 4mph when everything with the tune stayed the same. It picked up 8 mph from the edge and ran equal mph to the TSM car so it just needs to 60' better and you should be where you need to be. Keeping the rpm up higher should be all it needs.

I think it got hurt at Norwalk in the finals but not really sure. Hope to know more this week. Car seems to have lost power after that race. Its only been popped once, which was at the bpg race the day before eliminations. I went too high on the boost and it popped off the line but I let out right away.

 

[Dusty Bradford]

Is that 10.20 at 137 the best the car has ran so far with this engine combo?

 

[quickt]

Good info. It does look like the engine likes staying in the upper rpm range. Do you think the motor was hurt from the 10.20 pass to the 10.34 pass? Just wondering why it lost 4mph when everything with the tune stayed the same. It picked up 8 mph from the edge and ran equal mph to the TSM car so it just needs to 60' better and you should be where you need to be. Keeping the rpm up higher should be all it needs.

The 6 MPH gain ( 132 to 138 ) was from a 100 Shot of Nitrous. No spray car is back at 132ish. Notice his short time numbers they are still terrible even on the 100 shot. Kevin has posted his best numbers. The car has been much slower on average. Converters multiply or couple. Most all converter fluid couplers multiply when the input speed is higher than output speed. This converter does not seem to ever multiply making it very hard to accelerate the car to the 330'. After you get out where multiplication is no longer needed it seems to do ok. Maybe it takes even more power than Kevin's car can supply to make it multiply. At least we agree this converter is too tight for this car. IMO better suited for a car that is larger CID and has a much lower window of power.

 

[Dusty Bradford]

I see that 100 shot in the post now. He said he thinks the motor was hurt from the previous race so who really knows what's going on. It's better suited for a car that shifts lower or makes more power. I have over 1600 rpm worth of adjustment in these converters. His is on the looser end but can be loosened another 400-600 easily depending on which version it is.

As for getting it to 60' and 330, that's an odd issue because others who shift lower or makes less power don't have an issue getting to the 330 with the same part # as in Kevin's car. But loosening it to help with the rpm drop will help the car 60' and 330'.