I see so many people doing Top Swaps on our 3.8's. But, is it really necessary? I've done a bit of looking and have found that ZZP offers a bolt-on supercharger kit for the L36.

Does anyone have any experience with this kit? If so, would you do it again, over an L67 swap?

What are some pros/cons of sticking with the L36/L67?

Any help/information would be much appreciated. I'm about to start saving up for bigger/better mods. Also, would there be any extra upgrades that will need done for either?(Trans/fuelpump/etc?)

 

The thing about this is that the top end of an L36 wasn't made for boost, and GM is cheap so put those 2 together, and you would get a cheaply made top end that wouldn't be able to accept a good amount of forced induction. This is why the 3800 Camaro guys that keep stock internals recommend boosting an L36 to 5psi with a turbo (the Camaro 3800 can't be supercharged using stock GM parts unless it comes from an RWD Holden 3800 S/C due to the throttle intake being in the firewall if a FWD S/C kit is used)

With that being said, if you turned your L36 into an L67 via a kit, you would not be able to upgrade to a 3.4 pulley without damaging something in your engine. Keep this in mind. The easier and cheaper option is the top end swap.

You also have to beef up your transmission. The naturally aspired L36 uses the 4T65E trans while the L67 uses the 4T65E HD. The main difference is the internals. When the 4T60 was made in the early 90's, they had a tendency to fail when mated to a supercharged 3800. They were not made to handle much power. GM addressed this when they upgraded that trans to the 4T65 by having 2 different versions. The N/A and the HD for the S/C cars. So I recommend upgrading to the HD trans or upgrading your 4T65E to be on par with the HD version.

Also, you will need a tune. You can get a junkyard PCM from an S/C car BUT i believe some numbers must match your car's PCM so it can communicate with the BCM, otherwise the car won't run. The easiest way to do this I would imagine would be to see what numbers are on your PCM and match a specific one to a PCM on a supercharged MC. If you do some research (I had a link but lost it), you will find what numbers must match. I believe it's the "body number" or something like that. You could get the PCM out of another S/C W like a Regal GS or a Grand Prix GTP but the safest bet is research.

 

Ok here is my input. The zzp ssm90 kit uses a different supercharger belt routing and pull that runs off the regular belt unlike a l67 that has 2 belts. With that said doing pulley drops on a ssm90 kit is harder as you can only use pulleys that zzp offers for that kit because a l67 pulley will not work. As far as top end that really makes no difference I'm on l36 heads and l26 lim and uim with factory fuel rails boosting 19 - 22psi and making 500+whp with no issues. The main difference is l67 has the injector bosses in the heads where the l36 the injector bosses are in the lim. As far as bottom end the l67 has lower compression to accept boost better. The only difference between a hd trans and sd trans is the diff and gearing. Factory chain and gear set fail the same in both and neither diff has had many failures so hd vs sd trans i feel don't mean much just get what ever trans you have built with upgraded parts and at that time have them install a hd diff if you wish.

Last the zzp ssm90 kit is a ton of money and harder to upgrade because of the unique design of belt routing and it also uses a custom lim and fuel rail. My vote is do a top swap it's way cheaper and way easier to upgrade further down the road if you wish to do so.

 

I'd go with a full top swap. And the transmission doesn't matter, both standard and HD transmissions can hold the same amount of power (which is not much, like 300 BHP?). If it were me, I'd build the transmission from a NA 3800 just for the gearing, and might as well add an HD diff.

 

^^^^this


except for last statement, i though the hd diff is what gave the HD transmission the different gearing. meaning, you cant swap the hd diff into a non hd trans and still keep the 3.29 gears.

 

Nah man IIRC you can put an HD differential and keep the 3.29s, somebody please correct me if I'm wrong though

 

You can swap a hd diff into a sd trans no issue. Both diffs are the same gearing.

 

Top swap is the way to go for the most amount of power from an M90 engine. The higher compression gives it the real advantage. The SS M90 kit that ZZP offers is okay if you want a little extra power but costs a lot. Here's how I would list things from least amount of power to most and some pros and cons.

NA L36:
Pros: A good amount of bolt ons, nice for a little more power, for people who don't care about performance or will go turbo later.

Cons: Expensive, highest hp builds make less power then an L67 with bolt ons and a 3.4" pulley, virtually all new V6 powered cars make more hp then a heavily modified NA L36.

SS M90 kit:
Pros: Easy install, unquestionable gain in power

Cons: Exepensive, limited aftermarket, limited power gains

L67 swap:
Pros: Affordable, big aftermarket, almost a direct swap for 6th gen SS'.

Cons: High hp builds are expensive, will need higher compression for the most amount of power, a lot of work for the inexperienced.

Top Swap:
Pros: Affordable, big aftermarket, higher compression then an L67.

Cons: High hp builds are expensive, a lot of work but not as bad as a full L67 swap, you need to have some mods before you can run a stock size supercharger pulley (3.8").

Turbo L36/67:
Pros: Easy to make a lot of power (the "affordable" way to make 400+whp), pretty easy to find a good used kit for sale, and did I mention the power?

Cons: Higher initial cost but the more power you make the better the hp/dollar ratio, a bit of labor involved, tuning can be time consuming (but worth it).

I didn't mention a CSC build like mine just because of the rarity of it.

 

IMO, the ZZP kit is easier to install than a full top swap, but it's way more expensive. Back when they first came out, it was at least somewhat close to the cost of a top swap, but now that SCs are a dime a dozen, you could do 2-3 top swaps for the price of the zzp kit (assuming you aren't paying for install labor).

 

Is it just me but can you really even fit a supercharged l67 in our 5th gen montes? I mean I was looking at my engine bay the other day and I was like dang with that supercharger mounted on the passenger side of the engine it would be one heck of a tight fit. Maybe that's why GM offered the 90's Pontiacs supercharged and not the 5th gen montes. Maybe the Pontiacs had a little bit more room?