Boost and engine questions

[Onyx Dragon]

Hey gang. I've stopped in here before and asked questions about the 3800, even though I don't have a Buick, but a 2001 Grand Prix. I have been pointed over here from ClubGP.com before for cam questions, etc. My question now is of a different nature.

How much boost is a stock 3800's bottom end capable of handling? Perhaps my story might help a bit.

I have an N/A grand prix, with the 3800 Series II engine. I've decided I'm going to boost it, but with a blower, an M90 that I got a HECK of a deal on for only $350 including snout and pulley. I'm going to get a spare L36 engine to do the work on so that my GP isn't out of commission (yet ), and because it's just easier to pull pistons, cams, heads, add on headers, etc when the car isn't around the engine. I plan on doing some common sense upgrades, like swapping to the GTP heads (provided I don't lose compression from it..that's the key for me), putting in forged pistons with ceramic thermal coating and scuff resistant side skirts, intercooling it, upgrading my trans to the HD version the GTP has, headers as I mentioned, cam, high flow cat (already have a 3" cat back on it). Just the blower should theoretically net me about a 33% increase in HP at the crank (quick HP/torque comparison at the bottom). I've decided not to turbo it, as the turbo kits for this car are rare, and pricey (much like the new blower kits are), and I suppose I could scour the country for a wrecked GN to take a turbo set up off of, but I'm not sure it would fit this engine due to the differences in the top end of them. I have heard the bottom end of the two cars are similar, thus the reason I am here. I am in need of ANY advice you can give me on this swap, as well as any parts I may want to upgrade that I have missed. I would appreciate ANY and ALL constructive criticism you can give me on this. Thank you!

GT HP Stock: 200 After Blower: 272.6 hp (crank)
GTP HP Stock: 240 (crank)
GTP Comp G HP Stock: 260 (crank)

GT HP Stock: 160 After Blower: 218.08 (WHP)
GTP HP Stock: 192 (whp)
GTP Comp G HP Stock: 208 (whp)

GT Torque Stock: 225 After blower: 299 (crank)
GTP HP Stock: 280 (crank)
GTP Comp G Stock: 280 (crank unless they changed this, but I hadn't seen that yet)

GT Torque Stock: 180 (wheels) GT Torque After Blower: 239 (wheel)
GTP Torque Stock: 224 (wheels)
GTP Comp G Stock: 224 (wheels)

 

[SCREGAL]

I don't think that it is even worth it to try to put an M90 on an L36. From what I have heard, there are so many internal engine parts that you would have to change, it would be much cheaper to just do an L67 swap. As far as compression goes, L67's do run lower compression because they need to in order to support the blower.

 

[Onyx Dragon]

Originally posted by SCREGAL
I don't think that it is even worth it to try to put an M90 on an L36. From what I have heard, there are so many internal engine parts that you would have to change, it would be much cheaper to just do an L67 swap. As far as compression goes, L67's do run lower compression because they need to in order to support the blower.

Yeah, but I"m not worried about the whole "worth it" thing, this is going to be a project for me, complete with seperate engine to do the work on so I can keep my orig engine in to keep the car running, and as a backup in case of a blown engine. I've already located forged pistons with ceramic thermal coating and side skirts as well.

 

[nocutt]

Originally posted by Onyx Dragon
Yeah, but I"m not worried about the whole "worth it" thing, this is going to be a project for me, complete with seperate engine to do the work on so I can keep my orig engine in to keep the car running, and as a backup in case of a blown engine. I've already located forged pistons with ceramic thermal coating and side skirts as well.

Honestly speaking...it isn't really worth it...not because you cannot do it, but because of the way the M90 compresses!?!? you are already @ a fairly high CR, you will have to definately be intercooled or find a way to cool the incoming charge...then you are still going to be severely limited due to this bottom end. I am very sure you will not be able to make more than 9psi efficiently...just blower!!Now ultimately if you are really bent on doing this (and I KNOW YOU ARE lol ) as long as you can remove KR from the picture and use less timing on the street you can pull it off...it isn't any different than turbocharging...in principle
The bottom ends are quite identical but "seem" to differ in intergrity...IMO as long as you keep the factory set REV-limiter stock or better yet keep below 6K RPMs the stock rods will be fine! The culprit is detonation, you do not want any of it...for long at least...lol!!
NB: With just a bolt-on turbo from a GN you will be looking at almost 50% hp increase @ 7psi IC'd...and you cannot go wrong with 9.4:1 CR and max boost set @10psi

 

[Onyx Dragon]

Originally posted by nocutt
Honestly speaking...it isn't really worth it...not because you cannot do it, but because of the way the M90 compresses!?!? you are already @ a fairly high CR, you will have to definately be intercooled or find a way to cool the incoming charge...then you are still going to be severely limited due to this bottom end. I am very sure you will not be able to make more than 9psi efficiently...just blower!!Now ultimately if you are really bent on doing this (and I KNOW YOU ARE lol ) as long as you can remove KR from the picture and use less timing on the street you can pull it off...it isn't any different than turbocharging...in principle
The bottom ends are quite identical but "seem" to differ in intergrity...IMO as long as you keep the factory set REV-limiter stock or better yet keep below 6K RPMs the stock rods will be fine! The culprit is detonation, you do not want any of it...for long at least...lol!!
NB: With just a bolt-on turbo from a GN you will be looking at almost 50% hp increase @ 7psi IC'd...and you cannot go wrong with 9.4:1 CR and max boost set @10psi

Yeah, but finding a turbo off of a GN was the hassle I was running into. Anyway, I'm not just tossing a blower on, I"m buying a second engine, putting forged pistons with ceramic thermal coating on them in the engine, changing pushrods (just to be safe), probably go with roller rockers as well, getting head work done, a cam, headers, a high flow cat, already have 3" cat back, and an front mount IC. Also going to get the tranny upgraded to the HD tranny the GS and GTP have.

EDIT: Also..prob going to purchase a 4.0 pulley and "dumb" the boost down to 7.

 

[nocutt]

Originally posted by Onyx Dragon
Yeah, but finding a turbo off of a GN was the hassle I was running into. Anyway, I'm not just tossing a blower on, I"m buying a second engine, putting forged pistons with ceramic thermal coating on them in the engine, changing pushrods (just to be safe), probably go with roller rockers as well, getting head work done, a cam, headers, a high flow cat, already have 3" cat back, and an front mount IC. Also going to get the tranny upgraded to the HD tranny the GS and GTP have.

EDIT: Also..prob going to purchase a 4.0 pulley and "dumb" the boost down to 7.

You are finding hassle getting a GN turbo? Have you been to the "FS" section on this board?...lol! I understand the hassle of getting the plumbing and getting the right parts but you put one of those suckers on an L36 or L67 for that matter...sky will be the limit!...

 

[Onyx Dragon]

Originally posted by nocutt
You are finding hassle getting a GN turbo? Have you been to the "FS" section on this board?...lol! I understand the hassle of getting the plumbing and getting the right parts but you put one of those suckers on an L36 or L67 for that matter...sky will be the limit!...

I had forgotten about this board till recently or I would have looked in the FS section. OOPPSS