🔧 BUILD Turbo 3800 T56 Swapped G-body Grand Prix w/ Holley EFI

[SpeedSpeak2me]

So I am years late on commenting on this, but just wanted to say I have a real soft spot in my heart for this generation Grand Prix. I had a 79 SJ in, wait for it, Jade Green, with the anemic 301. Then had a pristine low mileage White 81 LJ with the even more anemic 3.8. Also always wanted an aerocoupe.

So,

 

[bs009]

That's awesome! Glad to hear that! Not too often you hear about other g-body GP's!

So now I guess I'm leaning more towards using my L67 then since the difference is too close to make a big deal about. Plus it'll feel nice to re-use that motor again since I still feel bad about getting rid of the car it was in before.

This article suggests there's probably more power on the table going lower compression with boost then since it would take a few more pounds of boost to match the effective compression ratios.

Boost Compression Ratio Chart

Best Boost to Compression Ratio Chart and Definition from RPM Outlet. How Much Compression can I run With a supercharger? Find out here

www.rpmoutlet.com

If their math checks out, then 20 psi of boost on the L36 would be roughly the same effective compression as running 24 psi on the L67 short block, and the 24 psi would give about a 7% power increase on the L67 vs 20 psi on the L36. The turbo and the intercooler would just be tested a little harder.

Looks like I have some room to play with cam timing too. Apparently the L67 cams are advanced a little bit compared to the L36 to give them a little more low end torque. If I use an L36 timing set I would get a little more top end power it looks like, but the L67 will help it get out of the hole.
I'll probably keep the L67 as it is then since I'm still using the highway 2.41:1 rear end in the car.

 

[Mr_Roboto]

So I am years late on commenting on this, but just wanted to say I have a real soft spot in my heart for this generation Grand Prix. I had a 79 SJ in, wait for it, Jade Green, with the anemic 301. Then had a pristine low mileage White 81 LJ with the even more anemic 3.8. Also always wanted an aerocoupe.

So,

I once posted a green Buick like that w/green interior on tb.com and everyone was fawning over the rare color combination. I'm gussing 301 NA right? A neat trick if you are into Pontiacs hard core is that an 81 301 dizzy will let you do computer controlled timing on a traditional Pontiac if you want to say TBI convert it. The 301 dizzys fit anything up to a 455.

If it was 05-10ish I'd say blow through the sucker and have fun till it popped. Any more though I'd be thinking about even a basic 4.8L with a lightly built 4L60E. Then again I'm betting the 110hp engine is paired with a 2.73 gear ratio or something absurd like that.

 

[bs009]

Working on this thing for the next couple weeks or so now instead of the wiki.

Got the motor pulled a couple days ago

Cylinder 3 was the only one showing any damage anywhere:

Head can probably just be cleaned up, but I have a set of newer heads I'm planning on using instead since I've heard the older heads can crack.

Here's the L67 shortblock I'm going to use:

Has about 225,000 miles on it. It came from my old 99 Regal GS that I don't have anymore. The motor is in pretty good shape for it's age and these things last forever anyway.

Figured I'd also do some porting while I have everything apart and switch to the L67 throttle body I have leftover too. It's about 4mm larger in diameter and has the newer style MAF sensor. I'm going to need to modify the intake a bit though like I showed in that L36 throttle body thread.

The intake will need to be opened up to take advantage of the larger TB

and apparently there's a huge protrusion on the bottom left of the opening that I thought was for the pcv but aparently serves no purpose that I can see...

anyway... it's gone now and there was nothing underneath it.

cleaned up the extra material welded on the intake so the throttle cable bracket fits:

Just removing that huge chunk of metal from that passage before should have a huge impact on throttle response and maybe power too so I'm pretty stoked to see the difference.

I'm also going to port the heads some. The F-body intake I have doesn't exact center perfectly on the the heads. One side is nice and even but the other side has a pretty big lip to it.

What's also weird is that there's 2 different curves between the intake and the heads. You can see it in that last picture but this is what it looks like:

Not sure if I'm going to bother doing anything with that though.

I'm definitely planning on getting some more room in the exhaust here though since my manifolds have the openings for it.

should be fun haha! I figure parts are going to take a while to get here anyway with the whole Corona situation so I might as well make the most of it.

 

[Mr_Roboto]

A few words of porting advice:
1-Leave the floor on the exhaust port the hell alone. It's dead anyways. You will lose flow if anything messing with it. You mostly want to raise the roof as much as you can. If you can get that whole 1/8" with out breaking through DO IT. You seem to be in really good shape to get it to seal. Maybe a bit on the walls but with that I'd be really inclined just to leave it be.
2-Gains from port matching will probably be pretty minimal even with the overlap
3-Shoot for .20D clearance around the valve at .25D of lift in the chamber where D is the diameter of the valve. That may not always be possible especially looking at this head's chamber. It doesn't look like there's any room along the cylinder wall side. Put a HG there, score it and go no farther. That's probably the quickest easiest power to make on it. This is a fairly modern chamber so a lot of that has already been done for you though.
4-The throats should be no more than 85% of the valve diameter. Get some washers or grind down an old valve in a drill to the diameter you want so that you can make it happen. You can stick it in and check your work as you go.
5-Smooth the edges in the chamber, should help your detonation resistance some

 

[bs009]

Here's the current progress on the heads.
I tried not to get too close to the valve guides, but I did open up the roof of the exhaust quite a bit and also cleaned up the bowl area too. I didn't really do too much to the intake though. Just cleaned up some of the casting edges in the head.

I set up both heads side by side so I could do a little at a time on each port and mimic what I did easier:

Exhaust before:

After:

Bowl area

before:

after:

I could probably go a lot further on the exhaust ports where they meat the manifold though I think.

 

[10sec]

Honestly, most of that is just a good excuse to drink a beer and spend some extra time in the garage. It does look good though

 

[bs009]

Thanks, that's probably true haha! It's kinda fun though at the very least. It's kinda like mowing the lawn because you can see the before vs after difference and it's pretty satisfying.

I've been watching a ton of engine masters and similar youtube channels lately and have been hearing a lot about how much heads can make a big improvement so I figured "why not?". There's a pretty good engine masters video about how Dulcich was able to make some pretty big gains on a set of old Mopar heads by porting and polishing them. He probably ported them way more than I've done, but still pretty neat.

 

[Mr_Roboto]

Thanks, that's probably true haha! It's kinda fun though at the very least. It's kinda like mowing the lawn because you can see the before vs after difference and it's pretty satisfying.

I've been watching a ton of engine masters and similar youtube channels lately and have been hearing a lot about how much heads can make a big improvement so I figured "why not?". There's a pretty good engine masters video about how Dulcich was able to make some pretty big gains on a set of old Mopar heads by porting and polishing them. He probably ported them way more than I've done, but still pretty neat.

Saw that video. Those were very racey heads. Relocated pushrods and (many of) the tricks. Dude is seriously talented.

As I said, raise the roof on the exhausts, open the bowls up and a little chamber work you'll probably see 80% with a lot less effort.

 

[v6buicks]

For sure. Dulcich is a really interesting dude in general. I like how he comes off as kind of a dorkey hillbilly, but actually started his career on Wall Street and spent a good portion of his life in New Zealand. Not to mention he could probably build a forklift out his barn with parts he picked out of the weeds that's faster than many of us . If there's one person in the world I'd like to sit down and have a beer with it's probably him. I can't imagine the wild stories he could tell.

 

[bs009]

Yeah he's definitely a super knowledgeable person about engines. He is a bit odd though haha! Biggest gripe about him I have is how much of an old-school carb-humper he is though.

I feel like him and Finnegan have some tension though. Kind of totally off-topic here but this old thread is kind of funny if you're a big Dulcich fan:

WHat's Freiburger up to? - The BangShift.com Forums

The strip had a nice race/show. Western Fuel Altered's Nitro cars / Alky cars plus a nice sized show. The pics are not great due to the suns position and my

bangshift.com

WHat's Freiburger up to? - The BangShift.com Forums

The strip had a nice race/show. Western Fuel Altered's Nitro cars / Alky cars plus a nice sized show. The pics are not great due to the suns position and my

bangshift.com

Really adds some color to this roadkill extra too if you can assume the two are related and that forum post isn't actually in jest as he claimed.

ROADKILL EXTRA: Season 29, Episode 613 - Rant at the Cheyenne Big Boy | MotorTrend

On Episode 85 of Roadkill, David Freiburger and Steve Dulcich road-tripped their Vanishing Paint Challenger across the country to Lincoln, Nebraska, for the Tire Rack SCCA Solo Nationals. Along the way, they stopped at the Big Boy Steam Engine in Cheyenne, Wyoming. As “Engine Masters” in their...

www.motortrendondemand.com

Might not be actually anything there, but the two were pretty weird together during some of the first episodes where Dulcich appeared.

 

[bs009]

I ended up taking a little more out of the exhaust ports at the flange, but didn't cut anything off the short side radius. Basically just took material off the top and smoothed everything so it's pretty close to what you suggested here.

Lapped the valves, and installed new stem seals:

Ended up not running this old 225,000 mile timing chain. It's looking pretty sad:

Head studs installed:

Engine relatively assembled:

Got pipe plugs? lol

Now I get to figure out how I'm going to attach the new throttle body's cable. The fwd cars have cables that pull from the front of the TB, but the RWD cars pull from the rear. So I need to figure out how I'm going to solve that issue. I'm thinking I'll be doing some welding of the bracket for the TB though.

Now that everything is painted this time, I'm also going to try to clean up some things under the hood too so the paint isn't hiding under wires and hoses and that ICM bracket. We'll see what I come up with, but I have a few ideas

 

[SleeperLS]

Looking good

 

[v6buicks]

Is there anyway you can take the throttles apart and swap pullies?

Nice work! I'm happy to see that this car will be back on the road in no time.

 

[bs009]

Thanks!

I was able to clearance a few things on the TB to make the camaro pulley fit on it, but it doesn't have the stops in the right places so it's easy for it to go beyond full throttle.

I'll either need to:
- keep the w-body bracket installed to be used just because the stops are in the right place and weld the camaro bracket on top of it
- attach some sort of stop in the perfect place for full throttle for the camaro pulley ? (not as confident about this option...)
- run a longer cable and just use the stock w-body bracket

I'll probably go with the 1st or last option. I think I have a really long w-body cable somewhere that I can use for option 3 and then that would get it out of sight too to help make things look cleaner.

 

[bs009]

Got it running today. Definitely still needs some work on the tune that I'm fixing right now, but it's way snappier now with the L67 throttle body.

ended up using the FWD throttle bracket and throttle cable. Worked out really nicely aside from me butchering the bolt hole where it bolts into the TB . Thankfully I didn't cut off all of the threads.
Also notice the stainless steel block-off plate I made for the IAC that was in the intake.

That evap line on the TB blew off during my drive and caused some crazy surge and made me go insane looking at the fuel trims until i figured out what happened

Intake looks so much better without cables all over it.

I'm trying to upload more to youtube to see if can get that to go anywhere. Definitely not enough 3800's on youtube IMO lol


I'll have a longer video up later

 

[v6buicks]

Dang man! You don't mess around! I'm glad to see it running so well. That thing looks like it goes as soon as you step on it. I look forward to doing the same. Maybe soon.

Agreed about the 3800s on youtube. All the good videos are getting to be ten years old. lol I need to figure out my sound problems so that I can contribute!

 

[bs009]

It's pretty lazy on the low end now that I did that cam timing change haha! The throttle response is night and day from where it was before though. Some trans tuning will solve that problem once the car is moving though at least.

I definitely took my time this time since I was filming everything that I was doing. Not a lot else going on right now though and it's kinda fun to just wrench on things without a schedule. I bought a gopro recently so I don't have to use my phone anymore but I'm still learning the ins and outs of filming haha

 

[bs009]

made this video for deboss garage's quarantine car show. Thought some of you might enjoy it

 

[v6buicks]

Love it! That description is such a roller coaster

 

[Mr_Roboto]

Your exterior portion missed those classy opera lights

 

[bs009]

Ended up pulling a spring out of the wastegate

 

[SleeperLS]

Yikes

 

[v6buicks]

Dang

 

[bs009]

Haven't had a lot going on with the car in the last year. Blame covid and other events in life keeping me insanely busy.

May not have mentioned that I turned the boost up on the car last year sometime over the summer by adding a set of 10 psi springs into it in addition to the 5 psi springs it had before. With both of those it would actually produce over 22 psi instead and it was taking it pretty well like that. Sometime early this year I pulled it out to visit a friend a few hours away and on the drive back I gave it the beans and was rewarded with a loud exhaust leak. After that I parked it until this past week since I've been working on getting ready to move.

So this past week I decided to fix the exhaust leak to pull the car out of the house. Pulled off the exhaust manifold gasket and saw some dark areas on it but overall it was in good shape. Replaced it anyways just in case but the leak was still there.
Turns out that the 'exhaust leak' was actually a blown head gasket ?

Anywho I pulled it out Saturday morning and had the new one in a few hours later. I didn't see any wear on the block or the head from it so hopefully it's fine. It does still have an exhaust leak though so I think I'll need to have the manifold mating surface flattened out.
Works great now though! I was able to drive it 9 hours down here to Tennessee. AC on it works better than any of the rest of my cars too.

Now I'm working on making a list of things to change on it before power tour. For sure the front suspension is going to get some much needed attention. If it's in the cards I'm hopefully going to address the transmission and rear gearset as well, but we'll see how that goes. New wheels are also on the way for this year because it needs new tires anyway