ajrothm

The converter is pitifully loose in 3rd judging by your rpm/speed/3.27 gears.

For comparison..

My 3600lb 71' vette, T400 with 3.36 gears/27" tires goes an average of 125 @ 5800 rpms with a tight 10" converter at the track. 137 mph (gps) is 6300. My converter average slip is 10%. (that is just using the Wallace online calculator)..

So check your trans, swap your converter. You can run with or without the electric kick down connected. Supposedly it increases line pressure somewhat, but I have made passes with and without it hooked up and it always runs the same.

jtotheizzo

Well racing season has drawn to an end here. Unfortunately the last chance to run was rained out. I guess we will have to live with a soft 11.16@120 for now.

In other news I did finally add a trans temp gauge.


Temps have seemed pretty decent so far though the average temp is like 60* ambient right now. ^ that picture was taken after a 20 mile spirited drive. The cooling fan seems to come on ~190-200 and off again around 180. I will be interested to see what temps look like after a full pull. I have tried building boost on the 2-step a few times and haven't really seen it impact temp at all.

So far the changes to Hygard, WOT switch, and raising the limiter have seemingly made some positive changes but its hard to really tell as traction is not the best on the street, and there are no good places to test near me.

Hopefully I will get some dyno time this fall since I cant race it. But I am already considering my options for winter upgrades.

toyin

Sucks you got rained out... Those gauges look pretty good im gonna have to get a set of gauges for my GN. Im really curious to see what you make on the dyno!

I ordered a 105 holley intake and just got off the phone ordering a custom turbo cam from Martin at Tick

Ive got the engine in but that's about it. I ordered a tranny jack to get the 80 in this weekend so we'll see how that goes. I need to order a tranny coolers like what your running. Probably gonna put it in the same place as yours.

jtotheizzo

Completed a couple upgrades this last week.

Installed an Eboost street and changed to an 11 lb spring in the gate. Boost starts about 200 RPM sooner and rises ridiculously fast. Where I used to only make 9 PSI at the top of first I make the full 15 and do so in less than a second. This chart shows before and after the changes and looks at a 1 second window:




Installed new headlights in the low beam positions and removed the High beams. I also added an air intake on the passenger side (idea stolen from Monte83) with ducting that goes to the air filter. I am amazed at what a difference that has made with my IAT's.



Shortened and installed the Center caps on my front wheels. From the factory they are huge and ugly but cut down they look ok I think:



All of this is in preparation to strap her to the rollers next Saturday. It's time to find out what kind of power she is making. Car is running like a top. Tune seems to be pretty good. 15ish PSI and 13* timing running a little fat up top at 10.9 AFR.

Any guesses as to what it will make?

3 window

iTrader: (1)

I don't really understand your graph.

jtotheizzo

I adjusted it to line the run up a little better hopefully to make it more clear.

The comparison is not as scientific as I would like but I am looking at what happens within 1 second of the transition to boost.

With the MBC set to 15 psi I would squeeze about 10 psi out at the top of 1st gear. Once I shifted to second it hit 15 right away. With the EBC setup also at 15 psi it hits 15 psi in first gear and does it so fast I am having issues shifting fast enough to not bang the limiter.

3 window

iTrader: (1)

Ok. I got the graph now. Big difference with the Eboost! As far as power, as long as the trans is figured out and not skewing numbers, with the stock cam, I'd guess 480 rwhp at 15 psi.

jtotheizzo

I think that is a pretty reasonable guess. My Trap speed last time out would tend to agree. I was hoping for more since that trap speed was short shifted and pretty sure the trans was slipping in 3rd. But we will see.

Trans seems pretty solid now that I have the kickdown hooked up and on hygard. I have been watching the trans temps and I have to work it pretty hard to even get it up to 180* so I don't think it is slipping any longer.

jtotheizzo

Took the cutty down to a dyno day yesterday. Unfortunatley the graphs are garbage but the end game was 603 HP/ 695 TQ on 17 PSI. Obviously I pushed it a little hard on that last run so I am certainly going to turn it down a bit.

Here is the vid:

Had fun, was able to drive the car home (always a good day), and I am happy with the results as that is right where I expected it to be.

Now the bad part. The converter continues to be extremely loose even spinning it to 6300. Looks like it will be coming out to be tightened. You know how I love a good chart so here it is:

3 window

iTrader: (1)

Nice power right there! Still the stock cam? You might never see a 10 second et, maybe go 9.90 first time back out! Huge difference. Keep us posted.

jtotheizzo

Yes stock everything except valve springs.

I would love to see it run 9's but I don't think it will. Been told a couple times that would be very hard to do on a 69mm gt45. Car weighs 3700 with me in it.

You know how dyno numbers are. Not sure I buy the torque numbers. Due to issues with the dyno the operator had to calculate them. So take them all with a grain of salt.

With the converter should I be concerned with my 27% slippage at the stripe or leave it alone because I cross the stripe in 3rd at my limiter?

3 window

iTrader: (1)

27% is a lot. Stay off the limiter. If it going to over rev because of the slip just let off. Dyno numbers are just numbers. Better for comparison when you make changes IMHO. Get it to leave and it'll run.

Forcefed86

iTrader: (4)

Much better numbers! That slippage is outa control though. If it is the converter that will make a huge diff.

I'd show that nifty graph to the guy that spec'd your converter and see what he thinks. If he' s not willing to restall that for free with almost 30% slippage I'd take my business elsewhere. Personally I'd go with someone that had direct experience with turbo LS converters. PTC/YANK/Hughes...etc.

jtotheizzo

Yep, talked to the converter guy this morning he says send it back and he'll make it right. He says he wants to see it about 10% slip and thinks that lowering it 800 RPM will get us there. He says he is doesn't want to do a full 1k because he thinks it may have issues building boost if he does that.

The more I think about it the more I think I'd rather have it tighter than looser. I am not done throwing power at this combo. I would be afraid that if I add more power it will be too loose again. I can always hit it with nitrous if I cant spool.

While I am getting good at it I do not want to have to keep pulling the trans.

Any thoughts from the experts?

3 window

iTrader: (1)

Not an expert by any means, however, that's the thing with the turbo converters, they're loose enough to build boost but couple up tight. Your converter guy should only be concerned with making it t

3 window

iTrader: (1)

Not an expert by any means, however, that's the thing with the turbo converters, they're loose enough to build boost but couple up tight. Your converter guy should only be concerned with making it tighter on the top end. As I understand it, good converter places can tighten a converter up top without affecting how it acts down low.

MileHighSierra

Sweet build! How hard was it to find a good G-body? It seems like all of them are utter s-boxes now, or guys are asking too much money for one. (I used to own a Grand National).

jtotheizzo

Agreed. I am sure part of the issue is I went the cheap route on the converter. Fancy stators cost money. I think I will spec it tight and throw more power at it to loosen it. There is always nitrous

I mean the issue wasn't finding a Gbody they are a dime a dozen. I drug this one out of a farmers field for $300. I am not sure I wouldn't say mine wasn't a piece of Sh*t though. It was quite a pile.

Now if you want a nice grand national then you will pay the price.

Forcefed86

iTrader: (4)

I don't know why anyone would target 10% these days. Depending on the core/parts used, that may be as tight as it will go and still spool the turbo with that unit? 6-8% is common.

The 9.5" nissan cores PTC uses along with their custom parts allow a higher stall than most on the line, then lock up tight on the big end. My converter feels very similar to a lock-up unit. It slips plenty down low (bit too much in the lower RPM) and then couples hard. I see less than 5% slippage up top and can make 20+lbs on the trans brake. 12 years ago when I started racing turbo buicks that kind of performance was unheard of. Seems common place now with the big converter names.

1970camaroRS

iTrader: (8)

Sweet deal dude. I almost went out to the dyno day at Ozzy, but I already hit up the one at TMS last month. Good to see another quick LS-swap Cutlass in the area. Going to come out to any of the Northwest Nights Motorsports events this year? Will be fun to line up with you.