I am seriously looking into a 4.9 swap...it looks quite straight forward and not too costly...I do have one question though.

I read that with the right manifolds and cross over (Y-pipe), the stock exhaust can be used with the 4.9. Has anyone done this? If so, could you post some pictures? I can't exactly visualize the configuration.

This would help my budget as I have a brand new Borla that I could use.

I just installed a 4.9 in my car and I as well was hoping to use my stock exhaust. I think it would be very hard because the manifold that sits near the rear firewall is very close to it. You could do it I guess but I don't think it would cost all that more just to re-do it. I paid around 400$ Canadian for True duel exhaust, bottle mufflers on each bank.

My Borla set me back $500US....and it has 0 miles on it...I would like to reuse it if possible. Do you have apicture of the back side of the engine that you could post?

Why would you want to choke your 4.9 with a restrictive exhaust, be it Borla or whatever! The 4.9 is almost twice the displacement and moves a whole lot more air. The exhaust manifolds on the 4.9 are much bigger than the 2.8 and will not mate to the Y pipe. We used the front manifold from the Fleetwood donor and the rear manifold from a Eldorado with these we did not have a cross over pipe above the transmission (it runs under the engine). We had a local muffler shop build the exhaust from scratch and it only cost $300.00, this included 2.5" pipe Y'ed into a 3" collector that hooked to a 3" in, dual 2.5 out Excelerator muffler. The Stainless Steel Tips added another $80.00. Don't choke your 4.9 the intake restricts it enough!!
Check rockcrawl's site for pictures of different exhausts that people have used "www.fieroaddiction.com" there is a wealth of info on the 4.9 swap there.

Joe Sokol
85 SE 5 Speed 2.8
88 Formula/GT 5 Speed 4.9 Caddy

I agree with fieroking... But if you really want to run the stock exhaust you can also modify the crossover into a y and have it run down to the stock location.

Well, I don't WANT to choke the engine...I just figured that the stock exhaust on the car was probably 2" or less, single outlet with a restrictive cat anyway....and that going with a single outlet low restiction exhaust without a cat might not be all that bad....just thinking these days...I would like to stay with a stainless system and I went through hell trying to find a shop that would fabricate the exhaust here in Motown (go figure!) and went with the Borla anyway.....I also do not want to remove the trunk to put in the exhaust....I saw those on Rockcrawls site and do not like the idea of cutting the trunk...

Anybody got pics of the crossover over the trans design? I have seen the one under the cradle and that looks promising, too! What cars had this crossover? (Early Devilles?)

Fieroking >> any pictures of your setup?

Having looked at this myself a lot lately I will make a point that is not really obvious...there are 2 different manifolds available on the 4.9. There is the 91-93 manifolds (with thanks to BubbaJoe) - these use the U-pipe that runs along the top on the transmission.

And then there is the 94+ manifolds (with thanks to Roackcrawl) (which are the same as the Eldorado and Seville (or look the same)).

So you will need to see which ones you have and then decide how you want to go, but you are best to install a new larger system with the motor. I would like to the the other side of the motor in Rockcrawls picture, so if anyone has it

Tim

[This message has been edited by Mickey_Moose (edited 04-02-2004).]

quote I just figured that the stock exhaust on the car was probably 2" or less, single outlet with a restrictive cat anyway....

The stock Cadillac exhaust is 2.5" going into the cat. I wouldn't even think of using anything smaller than that. Here is a picture of the Y pipe I make to route the exhaust in the stock Fiero location without cutting the trunk. It does require removing the engine mount pad from the cradle to make room for the pipe passing under the engine.

RockCrawl,

The last picture posted, with the exhaust coming straight out of the rear manifold looks pretty straight forward. Why would you NOT go with this method of installation? Is it just that no cat can be installed this way? It looks quite simple with only one preformed bend and another simple one....

Which manifolds are on this one? And I assume this uses the crossover over the trans on the driver's side (?) What mufflers fit this method?

Thanks for the responses...

quote Originally posted by rockcrawl: Here is a picture of the Y pipe I make to route the exhaust in the stock Fiero location without cutting the trunk. It does require removing the engine mount pad from the cradle to make room for the pipe passing under the engine.

How much do you charge for one of these custom manifolds? Can you still get a CAT on this setup? I have to pass emmisions in TX and I too would like to not cut the trunk.