Hey everyone,

I've heard people talking about the quad4 engine lately. As I remember, didn't they (at least the early ones) have some really bad problems with the heads?? Did GM get the problem squared away? Are they a difficult swap?

Thanks!

they had a problem with the head gaskets going at about 60-80k miles, but thats just the factory gaskets, ive heard that once its fixed, its fixed. difficulty? im not sure, u'll need to fabrocate your own engine mounts, and you'll need a quad transmission, the stock fiero ones arent compatible. all in all, id say the quad is a great engine for the fiero, for a 4 banger anyway

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88 Quad Coupe

MY EMAIL IS: sage14823@hotmail.com
"No bastard ever won a war by dying for his country. He won it by making the other poor dumb bastard die for his country."
-Patton

<--- (quad 4 guru)

These engines have a tendency to crack heads and blow head gaskets, they also feature a timing chain that can get noisy and is hard to replace. Quad 4 guys know there are two types of quad 4 heads, those that are cracked and those that are going to crack. The key (obviously) is to never overheat the engine. The alluminum heads on cast blocks caused problems with the head gaskets, but luckily FELPRO has made a great gasket that never fails. IF YOU REBUILD A QUAD 4 ALWAYS USE A FELPRO HEAD GASKET!!!!!!!

as for swapping them into fieros, I cant say, but i have heard that they are a tight fit, but the looks, and the power from a light 4cyl engine are incredible. im sure there are some swappers that can help you out more.

They're fun engines... Timing chains aren't as bad as it seems, plenty of space in the Fiero engine compartment to do it with the engine in. I thought they were fragile engines at first, but lately I've been beating on mine and haven't had a single problem.. yet. Mine has a little over 80,000 miles on it.

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1988 Quad 4 Coupe 5 speed click for more pics
1986 GT 5 speed
AOL: LastMinuteBastrd AIM: SavedbyJebus

The new anticapted swap is the ecotec engine. Supposely this can bolt up to the stock manual tranny.

I'll be doing an engine swap sometime within the next year. The two engines I'm thinking of are the Quad4 HO and a bored/stroked 2.8. My car has a Duke, so anything will be an improvement. The car will be used 99% of the time as a daily driver, so driveability and fuel economy are much more important than quarter mile and 0-60 times. That said, I do like to have a little fun behind the wheel from time to time.

The one thing that wories me about the Quad4 is the fact that it's rev-happy. I don't want to have to rev it to 4000RPM+ or whatever just to get some usable torque out of it. Is this a problem? Does the Quad4 have decent torque in the sub-3000RPM range?

I used mine as a daily driver for about a year. It'll pull from 2,000rpm no problem, but anything below that it's not too happy with. Well, I will occasionally chug around at 1500, but with my current exhaust setup it doesn't sound good at low revs.. As far as fuel economy, I've seen anywhere from 20-25mpg with a heavy foot around town, and above 30 on the highway.

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1988 Quad 4 Coupe 5 speed click for more pics
1986 GT 5 speed
AOL: LastMinuteBastrd AIM: SavedbyJebus

I"ve had a Quad H.O. in my GT for over 10 years and Im very happy with it. I put over 250 000 km with no problems at all, last year I baught a W41 Quad from a forum member and its even better than the H.O. Im looking forward to putting another 250 000 km on this one also. Most important thing to remember is to never over heat the engine and every thing will be ok.

my quad loves the higher rpm's, its like a normal 4 banger until u get to 3k, once u get beyond that, its a little rocket, loves to rev to 5-6k and more. u get used to it. most of the time i dont even rev it to 4k, not around town unless im feeling froggy

its a great engine in my opinion. ive kept pace on a lightning with mine, mind you he was pulling me, but not as bad as i would have thought. (read about it in my first loss/kill)

if i had a choice between a quad and a 2.8 stroked, id take the quad. i have a 2.8, and my quad will smoke it no problem, but i do like the rumble of the v6.

mine is my daily driver as well, and ive driven it all over the place, took it out to monterey and san-fran back in july, no problems/issues/ or complaints. one thing about the quad, u have good passing power at highway speeds.

its all personal preference. what do you want? also, the 2.8 would probably be much easier.

Shaddow I know what you mean, once you get the revs up there it is a little rocket. Just love putting it into 2nd gear and reving it to 7000RPM .....its a screamer......it just wants more RPMs....it seems sometimes that it can go for ever lol!!!

Ive put about 500 miles on my Q4 so far. It doesn't feel fast like my 3.4 P.R. does, but It will put a whoopin on it!
Its certainly not torquey (sp?) like any 2.8. It requires 93 octane gas, but pleasently rewards you with EXCELLENT gas mileage. I drove approximatly 220 miles (from Long Island, to about almost harrisburg, PA) and only had to put 6.3 gallons in it to top it off again. 35 MPG! Around town and heavy right footed, it can suck gas down as well, getting only about 22 MPG. But thats what you get when you have 180 (or more) horses. I don't know about others, but MY Q4 doesn't really start to kick till about 4500, and pulls progressivly harder till the 6800 rev limiter. I've been told that they start to pull hard at 3500, Maybe its my exhaust and greatly enlarged Throttle body. I went with the rare 3.94:1 Getrag transmission, and I feel that It's gearing plays a significant factor in how this car drives.
BTW, p8ntman442, I still want those cams

I don't have a problem with my Quad down low like I expected. Especially with 8.5:1 compression and the cams I have, I was worried about the low end, but the car has plenty of pull between 2k and 3k. If you are considering rebuilding thr 2.8, you could probably put the money in the Quad and have a beast! I'm making over 470hp and I got about 28mpg on the highway. Personally, I think the Quad fits the personality of the Fiero really well, much like people say about the 3.4 DOHC engine. It weighs about 100lbs less than the stock V6 and is a much better engine in terms of power and fuel consumption. Good luck!
--Bryson

Wow! this is a really interesting thread. Anyone know what a stock Quad 4 makes for horsepower? Whats the aftermarket like for the Quad? How hard are the upgrades to do?

Stock the HO Quad4 makes 180hp, while the W41 version makes 190 (different cam and ECU). The aftermarket isn't too great for them, I guess because they never really developed a following due to the head gasket issues. Most anything you do to the car you will have to do yourself, but that's half the fun and it's what makes your car unique. There are several upgrades off of certain years, like I believe the 1990 harmonic balancer was smaller (underdriving the belt), and the head with the casting ending in -086 is the best flowing head. You can port some on the exhaust manifold, and someone (I forgot who) made a 3.4 DOHC throttle body work with an adapter plate. Hope this helps!
--Bryson

I'm currently planning on rebuilding mine with lower compression pistons and better cams and some had work. I'm hoping to shot for about 180WHP, I managed 153 @ 5750 and 148.8 @ 4750 torque, when i went for a dyno run a month ago. Lets just say no one was expecting it. I had a 753 head and 90 crank pulley, manifolds, and ECU.

I plan for at least W41 cams, ported head, Pretty much rebuild the whole top end with good stuff 8.5 or 9:1 compression pistons, and maybe some pullies.

this is how my engine is built.

perrformance cams: .410 lift / .219 duration
Bored over .010"
Venolia racing pistons, 10:1 compression
Head shaved .015" for more compression
Ram air system (Holley side scoop, K&N filter in wheel well)
Custom exhaust - 2 1/4" pipe, high flow cat, Hooker Tuned Flow muffler
Lightened flywheel, new clutch
Larger fuel injectors
Many other new parts (lifters, sensors, ECM, wiring harness, hoses,

and i have the 3.94 geared getrag.

If you need aftermarket parts try www.mantapart.com

Check out mantapart they just developed a Super charger for the Quad

Mantapart Debuts 2.5 Liter Hybrid Quad Supercharger Engine

After lengthy development and testing, Mantapart has combined the best Quad 4 components with GMs SPO
supercharger kit and Electromotive's Tec3 EFI programmer to give a very potent new engine to the small GM
FWD crowd. Seeing the need to improve on the limitations of both the 2.4 engines and the SPO supercharger
kit, Mantapart has made many specialty parts and modifications to provide better power for these engines.

Mantapart has coupled the better flow of the earlier Quad 2.3 cylinder heads to a specially modified SPO
supercharger manifold. The increased flow allowed Mantapart to increase the displacement of the 2.4
engines and they also removed the power robbing balance shaft and weak oil system. Then by adding the
total engine management adjustability of the TEC 3 to the EFI , the power gains have been greater yet.
The basic sports 2.4 supercharger package engines are already at over 240 hp at the flywheel (nearly 200
at the wheel!) and the new hybrid 2.5 engines are looking at numbers close to the 300 mark. The results
are a very strong and reliable engine with power to spare for street or sports use.

Engine packages are available for most chassis models of the small GM FWD cars from '96 and up. Contact
Mantapart for more details and pricing on your specific engine and power needs.