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**1988GTU** · 04-16-2009, 08:10 PM

Why not drop a 3.1 in or do a full 3x00 swap?

**sakujo_kaji** · 04-16-2009, 09:49 PM

because that's just not as fun, and if i'm going to build it i'd rather use new parts, instead of used 3.1 parts.

**WrathOfSocrus** · 04-16-2009, 09:50 PM

Honestly with the prices for their heads and rebuild kit you could buy an entire rebuilt motor and save yourself a lot of work. If you want to build the motor yourself for performance you can build something much better than the ARI stuff and probably still save money. I would first suggest reading a lot of the threads here. I have spent months going through old posts and still learn new stuff often.

The 3400 and 2000+ 3100 top end will blow away the heads and intake your motor currently uses, and still be much better than using those ARI heads. The intakes are miserable for airflow and no kind of head work in the world will make those intakes flow well. It might not be easy to find low mileage 3400 heads but buying some higher mileage ones and having them rebuilt will likely be cheaper than those ARI heads.

All of the later Gen3 heads came with 1.6 : 1 ratio rockers from the factory and I would consider that to be standard for any 60 degree rebuild. The full rollers are particularly nice if you can afford them and are looking for performance.

For the rotating assembly, you can get a crank and bearing set almost anywhere. Online retailers, ebay, and local auto parts store to name a few places. It should come in a set with matched bearings and some places have core charges. I'm not exactly sure if they would hunt you down for turning in a 2.8 core for a remanufactured 3.1 crank. Rock Auto has 2 pistons listed under the 3.1 that both appear to be hypereutectic. One has a piston skirt coating that is highly recommended. For a slight bump in compression you can get 3100 pistons. The ones listed there for the 3100 only come with the skirt coating which is probably deliberate. $36.79 a piece when bought in a set of six. The compression calculator here says the Gen2 gasket is the same thickness as the Gen3? Never personally confirmed it but I'm sure someone here could. Or just use a head gasket to match the pistons you buy just to be safe.

Everything else seems pretty good. The 62mm throttle body wont fit your current intake, the bolts are in opposite corners. Maybe not impossible to make work, however it would take a large amount work to port the Gen2 manifold out to 62mm. And with how poorly it flows again going with the later Gen 3 top end like mentioned above would be worst the investment.

Also, consider getting a complete 3400 or 2000+ 3100. It already has the better flowing top end, slightly higher compression ratio than the Gen 2 2.8 and 3.1, and has better oiling. A little more work and a non vvt 3500 will make even more power. I personally pulled a Gen 2 2.8 from my Cutlass supreme and have a 3400 with 3500 heads waiting to go in. Just need a gasket set and to find a way to replace that horribly restrictive downpipe.

Good luck with the build! Don't make the same mistake I did and start buying too many parts before you learn what there is out there to give your build the best performance possible. I did get lucky on a few buys and got worked over on a few others. Reading all the free information available to you is the best thing you can do for your build.

**alainman15** · 04-16-2009, 10:50 PM

i agree with wrathofsocrus. i am in the process of building a 3400 and i think it is the right way to go. my 3.1L good engine but i dont expect mod gains to be as good as the same mods on a 3400. lots off people say that the 3.1L is restrictive. thats why they do the top end swap if they dont want the full 3X00. i think u might even save a lil money with the sawp and see about the same gains.
i think ur on the right track with ur mods but wrong engine.

**LeftVentricle** · 04-17-2009, 01:42 AM

Get a set of 3500 valves from the store if you're sticking with the Gen 2 heads. You'll need to do a valve job on the heads because the intakes are 0.040" larger, but it should be worth it. I've got a set myself, just haven't had them installed.

Also, high five Celebrity buddy.

**WrathOfSocrus** · 04-17-2009, 03:27 AM

Honestly the Gen 2 isn't all that bad, especially under boost. The TGP had Gen2 heads and intakes and with an undersized turbo made more power than the Gen 3 motors did, even if only marginally. Even with less oil galleys it can perform well for hundreds of thousands of miles with proper maintenance. My first encounter with a 60 degree was in my current car's twin that had over 230K miles before succumbing to the notorious coolant leak from that metal line that snakes around the whole engine bay. That car was the reason I admired 60 degree motors and when I found its better looking twin in the same spot the old one was found, it was a no brainer to pick that beast up for $100 even with a spun bearing due to abuse and lack of maintenance.

Obviously though a boosted Gen3 or even Gen2 with Gen3 top end would beat a stock TGP on a dyno any day. Before I found this site I picked up a set of rebuilt Gen2 heads for cheap and had planned on rebuilding my 2.8 as a 3.1. I also spent a ridiculous amount of time trying to port out the Gen 2 top end with an under powered dremmel knock off. Lessons learned.

I have had ideas rebuilding the old Gen 2 with the same plans as in this thread. I'm already stuck with all the parts to rebuild the 2.8 and have a completely different motor for my car already. An S-10 i tinker with would probably be a lot more fun with a supercharged Gen 2. However if I wasn't stuck with the parts and just had the old beat up engine I would bring it to a scrap yard and hope they don't charge me for the old boat anchor.

**sakujo_kaji** · 04-17-2009, 12:48 PM

thx for the comments and i did condiser the Gen2/gen3 swap, but i want to be able to pull the engine put the parts on and drop it right back without major mods, which the swap requires, and i was thinking of getting the ported Manifold for the 3.1L From WOT-tech, just forgot to add that at first. and besides with stock compression ratio i've been told i can safely run up to 15 PSI of boost so i'd think that would overcome the Gen2 Flow problems. and a set of MSD performance coils, fogot to add that to the first list too.

but anyway thatnks for the input and keep it coming.

**1988GTU** · 04-17-2009, 01:10 PM

A 3.1 mpfi is a direct bolt in, all you need to do is swap brackets and sensors to make it right.

**BillS** · 04-17-2009, 02:30 PM

Just a comment on the bottom end. No point paying for a complete bottom end with rods. Nothing wrong with the rods you have now, just buy pistons for whatever heads you end up using, and pick up a good used 3.1/3.4 crank and you are there.

On those pistons, it is really hard to build a conventionally tuned engine first and later turbo it. Compression is wrong and cam timing is also usually wrong. If you go low compression to suit a blower/turbo to be installed later, you won't be happy with the performence unblown. If you go high compression, you won't be able to use much boost unless you change those pistons.

A turbo cam normally uses much less overlap than a regular one (I'd g to a 272 sort of grind for conventional over the mild 260, BTW).

Sounds like you'd end up pretty much building 2 different engines to suit your alternative tunes.

Announcement

2.8 to 3.1 stroker possibly supercharged.

2.8 to 3.1 stroker possibly supercharged.

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