3500

[headbuster1221]

o1GAGT mentioned, in a different post, that he had a 3500 top end...my question is where can i get one that fits, how much power will it add and what exactly is considered the top end...

[MantaGreen97]

Several cars have the 3500 in it...

Note there are two versions of the 3500. One which is a wider-bore 3400 and the other which has a different bore/stroke. Both are of the 60degreeV6 engine family they just changed it for some reason after only a year or two of production.

To swap the 3500 top end to a 3400, you obviously will need the top end (UIM, LIM, and cylinder heads) and you will also need to drill holes on either side of the block where the 3500 uses gasket pieces instead of RTV to seal the block to LIM interface. The gaskets have little nubs on them which fit in holes on the block to stay in place.

You'll also likely need an EGR from a newer car as well, since your 99 car will have the older vertical mount EGR.

[O1GAGT]

I was the first to do the 3500 top end swap, and it worked out very well as they are pretty much a direct bolt on.

The 3500 heads in stock form outflow Milzy Motorsports stage 2 heads until .400" of lift. The stock cam lifts to around .420" of lift and if you ask any head porter they like to see higher low lift numbers, not to mention the velocity is much better on the 3500 heads due to a much better design.

Milzy's stage 2 heads cost $1,200 where as you can get 3500 heads for $300-$400 a pair. The choice is pretty simple if you ask which ones are the best value.

As mentioned above there are 2 versions of the 3500 engine, the one that you need are the non vvt heads from 04-06 which came in the malibu, G6, uplander, ect. Note you will also need the Lower intake as the 3400 intake will not fit the 3500 heads.

If you want to use the 3500 plenum (UIM) you need to buy an adapter and throttle body from the 60degreev6 store, or you can use a 3400 UIM and stock TB. To get the most out of this setup it is recommended that you go with the 65mm TB, but it is not necessary.

I just demodded because I am going to be selling my car in May, so I will be selling my headers and 3500 top end here in a few weeks.

For the money it doesn't get much better than the 3500 top end swap.

[headbuster1221]

how much increase in power will this provide and is it comparable to milzy's stuff (3.4) with P&P IM's (3.4)...

[DomestikDemon]

ooh, ooh, ooh, how much for the heads?

[headbuster1221]

if one has a LIM leak, one would assume that this would be correct due to the new gaskets used and the new intake manifolds, right?

[O1GAGT]

Correct, as you would be replacing the gaskets.

[DomestikDemon]

well, LIM leaks are simply a common problem on GM's 60* V6 motors.....Since day one, theyve been doing it.....2.8, 3.1, 3.4.....were all stricken with LIM disease

So ummm....its nothing to do with the gasket set...it just happens

[O1GAGT]

Originally posted by DomestikDemon
well, LIM leaks are simply a common problem on GM's 60* V6 motors.....Since day one, theyve been doing it.....2.8, 3.1, 3.4.....were all stricken with LIM disease

So ummm....its nothing to do with the gasket set...it just happens

I beg to differ, the new design gasket sets pretty much fixed the problem.

[nino_neg]

i remember reading that the 3500 swap helps with turbo setups with the air flow.. is this true?

[bballr4567]

Originally posted by nino_neg
i remember reading that the 3500 swap helps with turbo setups with the air flow.. is this true? If they are ported then yes, if not then no. Stock vs stock the 3400 outflows the 3500 but then when they are both P&P the 3500 is better for sure.

[O1GAGT]

Originally posted by bballr4567
If they are ported then yes, if not then no. Stock vs stock the 3400 outflows the 3500 but then when they are both P&P the 3500 is better for sure.

No the the complete 3500 top end flows alot better the the 3400 with out any porting.

What you are referring to is the 3500 plenum (UIM) on the 3400 LIM, with the 3400 heads. Once ported to better match the 3400 LIM it flowed more than the 3400 plenum. Porting the 3500 plenum is different than porting the plenum on the 3400 UIM as the 3500 has almost no runner legnth.


Also the 3500 heads are nice for those that are boosting because it knocks the compression ratio down to about 9:1 making them ideal for boost.

So the truth of the matter is, that the 3500 heads themselves flow extremely well at low lift's which is very important. I am willing to say that they flow better stock than 95% of the ported 3400 stuff out there due to the better design of not only the heads, but also the intake manifolds.

It is already known that the 3500 heads in stock form flow better than the MMS stage 1 & stage 2 3400 heads till approx .400" lift and MMS is considered to be performance gods by some.

GM really stepped it up and did their research on the 3500 heads and manifolds.

[bballr4567]

Yea I should of worded that differently for sure. Im still up in the air as to get the 3500 P&P as Ill be running a SC and have been told by some that running a lower compression on a SC is a bad idea but to be honest I havent checked it out myself.

[car audio dave]

from what i know, an FI setup should be run on lower compressions. with the lower compression you can run more boost (hence my buddy running 35 lbs in his grand national).