Turbo 3800 T56 Grand Prix

[bs009]

For sure! Now I should have all of the pieces to really put down some good power once that clutch arrives! The trans and the rear end have been the biggest weak links in this build for the longest time and a "hurdle" is a great way to describe it haha!

I'm still on the stock cam right now and really want to see what kind of power I can get out of it. I'm kinda willing to hurt this motor in the process if I have to, this one has so many miles on it so when I do swap over to a different camshaft I'll have a slightly better engine beneath it to get the most out of it. Right now the stock cam record is 497 whp and I think I can beat that since this is a stick car or at least come right up to it. The 9" is going to rob a little more power than the 7.5" 10 bolt though so we'll have to see.
You can run rockers and a camshaft at the same time as long as the heads can handle the amount of lift that would create. I think my brother was running 1.7 ratio rockers with his ST5 cam in his car at one point but I'm not completely sure. There are some benefits of running roller rockers though no matter what camshaft you have.
I have pretty high hopes for this turbo, I was hoping the exhaust housing would have been slightly larger but we'll see how it does!

 

[bs009]

Well Crap it's been a long time since I've updated this thread. Not too much has changed since then, just been driving the crap out of it whenever I can. The new turbo spools so much faster than the old one despite being so much larger everywhere.
My guess is that has a lot to do with the billet wheel on it, the similar size turbine wheel and larger compressor, and I'm suspecting the old divided T3 flange was restricting things a bit

The exhaust is tight but it seems to be working pretty well!

While I wait for my new clutch to get balanced I went ahead and swapped in a new clutch and flywheel. This is a Spec Stage 5 clutch, no springs and it's squeaky AF

Also finally swapped over to the 450 lph pump I had out here. Fun note, the factory wiring harness on the sender wasn't able to take the power draw that the pump needed. It melted the crap out of the connector so I had to drill it out, run a new power and ground through a grommet and RTV the whole thing with fuel-safe RTV

The new turbo sounds sooo good! No 3800 has any right sounding this good lol

 

[bs009]

Took the GP out to my first ever autocross event. I was kinda iffy on even going but oh my god I'm so glad I did!
I've never had so much fun behind the wheel of the car before and I think I'm hooked now!

I started off the day with a 74 second run, then managed to work my way down to a 70 second run, then worked it down to 64 seconds.
Fastest run I saw of anybody all day was 53.8 seconds. Most of the pack was around 58-70 seconds though that I saw. Huge turnout and I was able to get 5 or 6 runs in before I called it a day.

I never left 1st gear in this course and towards then end I had some trouble getting the transmission out of gear. I'm a bit worried the synchros might be unhappy but it could also be that the clutch isn't getting released all the way.
I managed to bend the rod for my clutch master cylinder or at least this was when I noticed the issue.

The car has some suspension upgrades: lowering springs, KYB GR2 shocks, 19mm hellwig pro touring rear sway bar, 34mm 3rd gen f-body front sway bar, and the boxed frame. But It still needs a lot more to really be competitive. The body roll is a little insane lol
The rear end is going to need more tire too because this thing really likes to kick the tail out coming out of the corners, the Quick Performance 9" with the TrueTrac really woke the car up big time and it was extremely noticeable on the track!

I managed to get a video without audio of one of the runs but the gopro mount wouldn't hold it very well. I'm going to order a suction cup mount though now. I have no idea why the gopro didn't capture audio, I've had nothing but issues with it

Here's my bent clutch master cylinder rod.

I'm going to try and revisit the whole pedal situation, maybe just redo the whole brake/clutch pedal assembly because it's really tight between all of the pedals and I know the clutch pedal has some flex in it that probably caused the bend. I'm sure the stage 5 clutch isn't helping either.
I think I'll just cut out a chunk of firewall too because the master isn't exactly lined up with the pin on the clutch pedal. Then I'll just weld in a thicker piece at the same area maybe.

I've also thought about going with something like a Wilwood pedal assembly but I don't want to take out the whole dash again in the garage I'm at. Would love to find a strong pedal assembly that just bolts in though.

 

[81cutlass]

I'll dig through my notes and show what I did for my master push rod, mine failed almost the same as yours.

Glad to see it's out! I'm jelly you can actually drive your stuff, were still deep in winter up north.

 

[81cutlass]

OK so I don't remember what pedal system you had (4th gen?), the master looks like a F body, I use a 3rd gen. Same difference.

Essentially what I decided is the OEM clutch push rods aren't strong enough to resist buckling loads when you put big clutches on them. An OEM master might be OK with an aftermarket clutch but the aftermarket master push rods are pure chynesium and fatigue over time.

Something else that helps is putting a brace from the floor to the pedal box to prevent the floor from flexing. I put mine in and it helped a lot (cut down part from an S10, but any 1/4 thick flat bar with a hole in each end works,

This is what I was running. 85ish S10 pedal bolted to the G body brake pedal box. I ended up shortening the pushrod quite a bit from what came as the replacement 3rd gen part and welded a coupling nut to the original eyelet end that connects to the pivot shaft on the pedal to gain some adjustability.

It broke on me at the track this summer after probably 10-15k miles. This is my emergency fix from Menards at the track to limp home.

Basically it folded right below where the minor diameter of the thread met with the coupling nut. The push rod on the master on the 3rd gen was like 2" too long for what I needed and the eyelet was a single piece and crimped on the 1/4" pushrod shaft that went into the master. I cut the eyelet off and the 1/4" rod on the master was threaded so I just made it adjustable.

I'm 99% sure the push rod shaft on your master is the same, that sleeve is likely just crimped on that 1/4" push rod shaft that slides into the master and contacts the actual piston.

I ended up buying a 3/8 grade 8 fine thread bolt and turning it on my lathe to match the original push rod ball shape

So that's what I ended up with

Having the spherical joint got rid of the squeeking that was in my pedal box.

 

[bs009]

Oh man that is a lot of work involved there then, you've done a really good job with that for sure!

Good idea about bracing the box to the floor, I will definitely look at doing that for mine now. The pedal box isn't very sturdy on mine so any bracing would be helpful I'm sure.

I am indeed running the 4th gen f-body clutch assembly with a pretty modified g-body/f-body pedal assembly. I ran the Holley adjustable master for a while before it started leaking but the rod was a lot stronger than the oem replacements. It has a small spherical joint in it to help a little too. I think mine failed though because of either the side to side play in my pedal or that the firewall hole isn't perfectly lined up with the pedal button deal. Eventually I was able to push the pedal to the floor without any resistance at all so I think fluid was leaking past the piston internally in the master.

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Sounds like for a long term solution I really should just bite the bullet and go with an aftermarket pedal assembly then

 

[bs009]

Went ahead and started looking at this again. It definitely needs some form of bracing for where the clutch master cylinder meets the firewall. My holes are a bit wallered out and that didn't help at all, but the sheet metal surrounding the clutch master cylinder was pretty destroyed. I'm assuming they didn't intend the firewall to be able to support that kind of pressure in such a small area when they built these cars.
I see now why the sickspeed monte kit has such a thick piece of metal that bolts onto the firewall and the 4th gen f-body pedal assembly has a brace that runs from the master to the pedal box. In hindsight that probably would have been the easier/cheaper route to take now that I've destroyed 2 clutch master cylinders (one of them being a $200 Holley master).

SSM Clutch Pedal Kit (Designed for F-Body Master Cylinder) – Pro-Touring Products

A G-Body hydraulic clutch pedal setup that feels like an OEM vehicle.

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So here's my mangled up firewall after cutting out the mounting point

I started off by cutting the holes into a 16 gauge sheet of metal then bolted it up to an old master I had lying around to see where it wants to be once it's attached to the clutch pedal

Tacked it in afterwards

and welded around it 360*

This alone felt way stronger than it did before, the clutch master wouldn't move at all with it like this.
I wanted to add a brace to the pedal box though too so I started building a piece I could use for that separate from the firewall that would be a part of the pedal box using 1/8" thick steel

added some sloppy angle iron to make it more rigid

It looked like I'd have to take the whole dash out to get to the pedal box though and I really don't want to have to do that right now this year so I just left that piece bolted on. This should still be way stronger than it was before and maybe that extra 1/8" thick piece is helping a little too even without being welded to the pedal box yet.

I added the new master cylinder again now and the clutch feels 10x better already though so I think this might be enough of an improvement to get by

This morning though I'm wondering if I should take off the fender liner again and see if I can add a brace like the sick speed kit does though between the brake booster and the clutch master on the engine side of the firewall. It would basically accomplish the same thing as bracing it against the pedal box.
I might be able to get the booster bolts off without too much of a hassle and if the spacing on the master pulls the brake pedal closer to the floor that might not be a big deal. For some reason I was thinking I'd need a longer brake booster rod for the pedal if I added a brace between the booster and the firewall. What do you all think?

 

[84dragcutlass]

On power tour last year did you and your car run down the highway with a L67 powered silver buick LeSabre? I think i saw your car a few times. I was a black L67 powered Intimidator Monte Carlo. From what i saw later that Buick blew his transmission a few cars ahead of me coming through a small town. Bummer for sure. Haven't decided what im taking for power tour this year. Will probably end up being the Monte as long as i can get the new cam put in it in time. Like the thread ive always wanted to do a RWD L67 they have some power

 

[bs009]

On power tour last year did you and your car run down the highway with a L67 powered silver buick LeSabre? I think i saw your car a few times. I was a black L67 powered Intimidator Monte Carlo. From what i saw later that Buick blew his transmission a few cars ahead of me coming through a small town. Bummer for sure. Haven't decided what im taking for power tour this year. Will probably end up being the Monte as long as i can get the new cam put in it in time. Like the thread ive always wanted to do a RWD L67 they have some power

Yup! That was us! We actually tried to find you a few times since we saw your car and I believe you even ran it on the drag strip too.
The Buick Lesabre is twin charged so it has a turbo in front of the supercharger too. He was able to put down 497 whp down at the dyno on Power Tour and broke the stock cam record! Mine didn't fare as well last year but I'm coming back with a vengeance for this year lol

He did indeed break the transmission doing a burnout in a small town there on the way to the last venue. I waited with him for a while for another friend to bring a trailer before he had me just go on without him in true Top Gear fashion lol
Awesome story there though, the shop he broke down in front of actually let him use their lift to see what happened. While they were there another local actually happened to have some spare transmission parts for the 4t65e and was willing to donate them! Between the shop who let him use the lift and a local named Bill they were willing and able to help him get back on the road the same day. He didn't make the last checkpoint but it was super cool of them to let him use a lift in their shop and for them to donate parts to get him back going again!



Everyone involved in Power Tour is a seriously awesome group of people! He and I will definitely be back again this year, I believe he's taking the same car too. My brother was with us the first few days in his L67 swapped Montana, but had to take his son home after the second day. He'll be going with us again this year but should hopefully be long-hauling again too. We're also trying to get a third person with an L67 swapped 80's Bonneville to come too but I think he's going to need some convincing lol

Be cool to run into you this year! The days on Power Tour can be long and a little stressful so I might not look friendly but I promise I try to be lol

 

[84dragcutlass]

Dude thats awesome I knew that was the car. Hope to see you this year. You're right on power tour being stressful. Luckily my wife goes with me. Hope to see you guys there this year for sure! His car looked pretty awesome. Mine is lucky to make 350 to 375 with the new intercooler so almost 500hp is enormous. Great work on your car btw