Customer Experiences

Scott Perkins - 4.9 Conversion Recipient

Since getting the 4.9 V8 conversion from The Fiero Factory installed in my Fiero, I put 30,000 miles on my car. I drove my car from Cincinnati to Los Angeles and back, during the hot summer in August. I drove it through the hottest part of the desert, up long steep hills at high speed with the A/C turned on, and the temperature stayed below 200 degrees except for one five minute period when it hovered around 220 (The red line is at 240). Most of the time the gauge stayed right on 180 degrees. The engine bay even stays cooler now than it did with the original V6 engine. I drove through the mountains in Colorado at over 10,000 ft altitude. The engine had no trouble adapting to all these conditions, and ran well on the 85 octane gas they sell up in the mountains.

It was near Vail at high altitude up in the mountains that I learned my car now has more acceleration than an Audi A6 2.7 Twin Turbo ($43,000). As far as the installation of the engine goes, there was only one very minor issue in the first 30,000 miles. I found a transmission line with a rubber hose clamp which had some visible fluid clinging around the clamp. It was a very slow leak, an ooze rather than a drip. The problem turned out to be a defective hose clamp which had been tightened but would not tighten up far enough. I replaced this clamp, and have had no other issues.

I have had perfect reliability so far, and the car is trouble free to use as a daily driver. No failures to start, no acting up, and nothing has come loose. I haven't even had to tighten a belt. The gauges work perfectly too. All I do is change the oil and put gas in it, then drive some more. To have this level of performance combined with such low maintenance, great gas mileage and full-coverage insurance for only $700 per year, is about as close you can get to automotive bliss in a daily driver. The Fiero Factory conversion has held up very well. Great job guys!

Why I Chose The 4.9 V8 Conversion

I use my Fiero as a daily driver, and like many Fiero owners, I wanted more horsepower than the stock engine provided. I considered many ways to boost the power, and came up with a few of my own priorities. Of course, other people will have their own priorities, but just for fun, here are mine:
1. I'm not quite rich enough to justify spending over $10,000 for an engine. I had to keep the expense down to earth.
2. I like the handling provided by the stock suspension on the 88 GT, and I wanted my car to handle the same with the new engine.
3. The more high-RPM power the better, but it couldn't substitute for low-RPM power. After all, I use the car as a daily driver.
4. My old 2.8 V6 engine was already worn out, so even if I bought a turbocharger, I would still have to buy or rebuild an engine to go with it.
5. I didn't want bad mileage.
6. It had to pass the smog check in Ohio.

One way to achieve priority #1 was to pick an engine and transmission combo which weighed no more than the stock engine and transmission. This saved me $900 by avoiding the expense of new coilover struts and stiffer springs. This weight saving approach also met priority #2, because I wouldn't have to modify the suspension. My money and weight limits eliminated the cast-iron small-block V8(5.7L) and Northstar V8(4.6L) as engine options. Both were too heavy, and in addition, one of these conversions was too pricey; guess which. As for my priority #3, the Caddy 4.9 V8 makes around 150HP at only 3000 RPM. In stark comparision, did you know the famous 240HP S2000 engine produces only 50HP at 3000 RPM, and only 25HP at 1500 RPM? This is less power at these RPMs than the original Fiero 4-cylinder. Needless to say, I didn't want a tiny engine.

BTW, the S2000 is an interesting comparison because it weighs about the same as a Fiero GT.
3000 RPM Horsepower GM 4.9 V8 150HP--GM 2.8 V6-75HP--GM 2.5 L4-61HP--S2000 VTEC 50HP
1500 RPM Horsepower GM 4.9 V8-75HP--GM 2.8 V6-38HP--GM 2.5 L4-31HP--S2000 VTEC 25HP.

The 4.9 V8 would meet priority #3, yet so would the very smooth 3.4 V6 with a turbocharger added. But since I needed a new engine anyway, the cost of the 3.4 V6 with turbo was going to be close or maybe more than the 4.9 V8 conversion. Priority #5 steered me away from the Supercharged 3800, because word on the street was the 4.9 gets better mileage. And the 4.9 has more low-RPM power, because superchargers just don't do much at low RPMs. There were a couple of other nitpicky issues with the supercharged 3800, which caused me to favor the 4.9. The alternator gets in the way of the Fiero trunk-lid lift spring, requiring the substitution of one of those leaky gas struts like you find on a hatchback. And the 3800 is an old-fashioned 90 degree V6 which is not as well balanced as the more modern 60 degree V6 (GM 2.8, 3.1, 3.4L engines). The 3800 requires a balance shaft to be smooth.

These are small issues, and honestly the 3800 might have been my choice if there was no 4.9 V8 conversion available. The only thing the supercharged 3800 had in its favor over the 4.9 was about 25 more horsepower at high-RPM compared to the stock 4.9 V8. I chose in favor of the low-RPM power and smoothness of the 4.9 V8, knowing it's always possible to add tuner parts to the V8 to get the 10% extra high-RPM power, or maybe much more.

Though I wasn't sure at the time, I can now report that the 4.9 V8 actually smog tests much better (65% less smog) than the original 2.8 engine , and it gets better highway mileage too at 28MPG. The old engine never turned more than 27MPG on the highway with the 5-speed stick shift. An additional highly important factor in my decision was the quality of the 4.9 V8 conversion available from the Fiero Factory. This has to be one of the nicest installations I have ever seen for an engine conversion. It looks just like it would look if GM had built the Fiero with this engine from the factory. I have had many people look it over and say they never knew GM put V8s in Fieros. The wonderful clean wiring job is a must have item. And this conversion provides for using the factory computer, so there is no problem with emmisions control. Also the factory computer is needed to operate the electronically controlled 4-speed Cadillac automatic transmission. If you want this excellent transmission which maximizes the fuel economy of the 4.9 V8, you will need a conversion which includes the factory Cadillac computer. Oh, and there is one more little reason I had for choosing the 4.9 V8 conversion for my Fiero; it makes it fast!

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