Question about ported exhaust manifolds (Page 1/2)
Cliff Pennock MAY 26, 03:55 PM
About 10 years ago, I got myself a set of stock manifolds and ported them. But I never got around to actually installing them. I'm now thinking of finally installing them but I'm wondering if it's really worth the trouble.

I understand the gains are about 5-10 HP but do you really notice a difference? And if so, is that difference "Holy Crap!", "Cool!", "Oh, ok", "Eeehhhhmmm" or "Really? All that trouble for this"?
Patrick MAY 26, 04:34 PM

I have ported exhaust manifolds on my Formula. Did I notice any difference in power? Not really... but I did notice a difference in the sound. It's nice.

Would I go through all the trouble of swapping the exhaust manifolds just for that if there was no other reason to remove the stock manifolds? No. You'll probably end up breaking one or more exhaust manifold bolts, and they are a b!tch of a job to drill out with the heads on the engine in the car. However, if you've already got broken exhaust manifold bolts (and a leaking exhaust), by all means, install ported manifolds while you have everything apart!
Cliff Pennock MAY 26, 05:39 PM
Well,I love the sound of the stock V6. If that's going to change without any gains in performance then I think I'll just leave things as they are.

About 10 years ago, I had the Edelbrock performance camshaft installed which set me back about $800 at the time. I noticed no difference in performance whatsoveer. They told me I would not notice any difference unless I also installed the ported manifolds. I always suspected I got ripped off and they never installed the performance camshaft at all.

But could that be true? That I only get a performance gain out of the camshaft if I also install the ported exhaust manifolds?
Patrick MAY 26, 05:55 PM

quote
Originally posted by Cliff Pennock:

I had the Edelbrock performance camshaft installed which set me back about $800 at the time. I noticed no difference in performance whatsoveer. They told me I would not notice any difference unless I also installed the ported manifolds.



There are other members here who know a whole lot more than I do about engine breathing... but sure, I suspect ported exhaust manifolds would help allow a "performance" camshaft to do its thing... unless the intake restrictions are also cramping its style.


quote
Originally posted by Cliff Pennock:

I always suspected I got ripped off and they never installed the performance camshaft at all.



When I installed my 1.6 roller-tipped rockers, I definitely noticed a difference in idle quality (somewhat lumpy idle), but I can't say I noticed much of a boost in performance, even with the ported manifolds.

You can get an idea of what my Formula sounds like Here (or from other videos I posted in that thread).

[This message has been edited by Patrick (edited 05-26-2020).]

Jake_Dragon MAY 26, 06:28 PM
If you still have the stock Y pipe you may want to research that as well.
I would be afraid of breaking the bolts off, but if you do it you should upgrade to studs.
Good luck.
Dennis LaGrua MAY 26, 07:40 PM
Back when Fieros were new, a noted racer and engine builder by the name of Herb Adams did some dyno tests on the 2.8L engine. He claimed that ported manifolds did give the engine 8 additional HP but I believe that he was using a less restrictive crossover pipe or true dual exhausts. Running with a straight pipe did not produce any more power and adjustments to the chip program in the chip showed no gain and that GM had in fact had it optimized.
Full article here:
Herb Adams Dyno Tests

[This message has been edited by Dennis LaGrua (edited 05-26-2020).]

Raydar MAY 26, 09:10 PM
I would kind of concur... Replacing the manifolds, for no reason other than the slight reduction in restriction, or the slight increase in sound, is probably not worth your trouble. It's a bit of a pain on a good day, and will cause your to break out vocabulary that you seldom use, if things go bad.

If the cam that was installed is not optimized to the rest of the engine (or the engine optimized to the cam) you might have noticed a bit of change to the exhaust note, but probably not much else. Would you, by any chance, know what the specs were for the cam? Or even a model number?
Dennis LaGrua MAY 26, 09:30 PM

quote
Originally posted by Cliff Pennock:

Well,I love the sound of the stock V6. If that's going to change without any gains in performance then I think I'll just leave things as they are.

About 10 years ago, I had the Edelbrock performance camshaft installed which set me back about $800 at the time. I noticed no difference in performance whatsoveer. They told me I would not notice any difference unless I also installed the ported manifolds. I always suspected I got ripped off and they never installed the performance camshaft at all.

But could that be true? That I only get a performance gain out of the camshaft if I also install the ported exhaust manifolds?



Cliff: You can check valve lift. The stock cam specs are in the manual. Take off the rear valve cover and using a dial indicator rotate the engine ignition off ( with a wrench or with a remote starter switch) until the valve lift is lowest. Zero the dial indicator then rotate to measure the total maximum valve lift. A performance cam should have more lift than stock.

------------------
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RWDPLZ MAY 26, 09:54 PM
Unless the car has an exhaust leak or you need to get them out of the house or something, I would leave them alone. Lots of horror stories on here of exhaust bolts breaking off in the heads on V6 cars. Pulling the heads on the 2.8 is VERY involved if that happens, and I would think replacements or a decent machine shop are even harder to come by over there than here.

The fact Kent Moore made a specialty tool just for that job back in the day just screams 'if it aint broke don't fix it'


quote
Originally posted by Patrick:

KENT MOORE J-38782 FIERO 2.8L EXHAUST EXTRACTOR KIT. It bolts to the head and guides the drill bits so that the broken studs can be drilled out straight. I snagged one on eBay a few months ago because I knew I'd need it. Here's a couple of images I picked up from the 'net.
seq MAY 26, 11:38 PM

quote
Originally posted by RWDPLZ:

Unless the car has an exhaust leak or you need to get them out of the house or something, I would leave them alone. Lots of horror stories on here of exhaust bolts breaking off in the heads on V6 cars. Pulling the heads on the 2.8 is VERY involved if that happens, and I would think replacements or a decent machine shop are even harder to come by over there than here.

The fact Kent Moore made a specialty tool just for that job back in the day just screams 'if it aint broke don't fix it'



If you're in the market for one, it seems Rodney Dickman makes them too