go to:
http://home.attbi.com/~dias1179/Fiero-dyno-011803.jpg

Ok, you can see I had lots of trial and error runs...
i played with the timing from runs 4 and up... I was way retarded to begin with.

I also used my BIG accel coil on runs 2 and up so the only change from run 1 and 2 showed a 1 hp dain and 4 ft*lbs from 1500 - 4100 so the coil does help...

For run 3 I unbolted the EGR and mounted an L-shaped 3" exhaust pipe over the open egr...

this resulted in a 8 hp gain and a few ft*lbs of torque.... This tells me that the stock Fiero exhaust system is WAY TO RESTRICTIVE for the 3.4. BTW, I have an exploded muffler so I think a 3.4 needs closer to a 2.5 inch exhaust.

for run 4, I advanced the timing a bit... gained another 1.5 hp so I advanced it some more but lost my bearings and over did it. Pinging! Lost lots of power!! So for the next several runs I kept nudging it back and back. This was taking too long and it was getting late so we put the EGR back on (it's blocked off from going into the intake anyway) and the shop owner, Mike Dez(great guy), pulled out the timing light... I must have retarded it 15 degrees when he said that looks about right so one last run and boinG!!!! 149.8 hp!

So I think I will be going with a custom exhaust soon and try to reach 160hp and 210lbs*ft which I think is VERY DOABLE.

oh yeah...almost forgot... run 6 was without the air filter in... I think I lost a couple of ponies up until over 4500 where it really allowed the motor to breath and let me make 145-147 from 5000-5500 rpm more or less so I think that damn air silencer/water separator needs to get punched out and get the best of both worlds...

If any of you have followed my other threads then you already know my mods...

that sounds pretty good
so is that 149hp with the exhaust fully in place?
I dont remember if you have headers or not but i think the stock crossover pipe is a much greater restriction then the rest of the exhaust.

yes (149.8 that's 150 in my book) EGR on and holes in my muffler
EGR off gave me an 8 hp gain with bad timing... I estimate a 10 hp gain with a proper exhaust.

some pics:
http://home.attbi.com/~dias1179/fierodyno1.JPG http://home.attbi.com/~dias1179/fierodyno2.JPG http://home.attbi.com/~dias1179/fierodyno3.JPG http://home.attbi.com/~dias1179/fierodyno4.JPG

quote Originally posted by lou_dias: For run 3 I unbolted the EGR and mounted an L-shaped 3" exhaust pipe over the open egr... this resulted in a 8 hp gain and a few ft*lbs of torque.... This tells me that the stock Fiero exhaust system is WAY TO RESTRICTIVE for the 3.4. BTW, I have an exploded muffler so I think a 3.4 needs closer to a 2.5 inch exhaust.

Have you ever looked inside of the stock fiero muffler? it is HORRIBLE. It looks like the only way for exhaust to get out is through all of those little cheese-grater sized holes! I'm sure that bigger size pipe itself would help.

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1987 Pontiac Fiero Coupe #18,838
3800 Series II SFI; 4T60-E Trans w/ 3.33 final drive; Terminator exhaust; 4 wheel vented disc conversion; Walbro 307 fuel pump; W-body air box w/ K&N filter; Rear 32mm sway bar; 134a functioning A/C; GM Pontiac CD player 7-band EQ w/ factory location sub; much more and...a stock GN's TURBO on the way!

Conversions Performed:

1985 SE 3800 Series 1 SC 4T60-E
1987 Coupe 3800 Series II 4T60-E
1987 SE 3.4 TDC 5-speed

http://dtcc.cz28.com

I'm thinking 3" after the cat then when it turns the corner sticking a 3" diameter Bullet muffler then when it reaches where the muffler would be, make a T and go 2.5" each way and instead of tips I want to use 2.5" Bullet mufflers... They are about a foot long.

Assuming a 15% driveline loss that comes to 179hp going into the trans. Isn't it a b!tch trying to pull power out of this engine?

Dave

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- Electron Blue '88 GT 5-speed (1 of 1): Before After ZZ430 Ram-Port FI--Wanna Race? Follow it here on the Forum!
- Silver '88 GT 5-speed (1 of 139) w/cammed 3.4
- '98 6-speed Corvette Coupe, '87 Coupe SOLD!

quote Originally posted by crazyd: Assuming a 15% driveline loss that comes to 179hp going into the trans. Isn't it a b!tch trying to pull power out of this engine? Dave

for some reason, I believe 25% is more accurate

the ***** is the exhaust, a proper one can extract another 15 hp, I will try to save some oney and shoot for 10-12 hp.
without an air filter, I gained 15hp in the 5000-5800rpm range so something can be done there as well

if you assume a 25% loss from 200hp then that is 150hp we could compromise and say 20% and that's 190hp and it's still nothing to sneeze at.

That's more than the Montana's 180hp.

I will break the 160rwhp barrier in a month. Mark my words...

I also made some good contacts for a custom crossover for a turbo and may be picking up a Grand National turbo for $75...

quote Originally posted by lou_dias: for some reason, I believe 25% is more accurate

It's probably closer to the smaller end of 15-20% loss as front wheel drive cars are more efficient and don't have the traditional 25% loss of a front engined/rear drive car since there isn't a long driveshaft connected to a rear differential that increases the total loss %.

The Fiero is essentially a transverse front drive setup with the engine in the back, so crazyd is not that far off.

Ken S.

From what I've read, It's generally 15-18% for manual transaxles and 20-25% for automatic transmissions. There is more loss thru an auto than a manual. There is a place by me that uses 18% for manual and 24% for auto's as a reference. I've been talking with them about doing an engine dyno on my 3.4L. They said it would cost about $350 and they would run the engine at 2000 rpm for 25 minutes first to break in the internals. (required) I haven't decided yet, but at least I would have a very accurate reading on my engines true output.

What kind of cyinder head mods were done to this engine? From what I've seen by other 2.8-3.4 swaps the HP gain isn't all that great considering the displacement change. Are 2.8 and 3.4 heads identical as far as port volume, valve size and combustion chamber size/shape? Did you go all out in the 3.4 cyl head, i.e. porting/bench flowing, tuliped oversize valves, roller rockers, cam, etc? Sorry if I missed anyting about your build up, been away at sea for awhile.

Parts list:

GM performance cam .427/.452
Sprint Exhaust manifolds
Darrell TB + intake
ported lower intake
lightly ported middle intake
ported and polished heads (they unfortunately flattened that vane that your not supposed to)
1.52 roller rockers
K&N
85K+ used 3.4 engine
NGK plugs
Accel BIG coil
45psi adj. fuel pressure regulator
Tomco injectors
blown-up cat. converter (but externally sound)
muffler with holes from blowing up cat

at WOT my a/f ratio was under 13:1 across the board

I don't understand how people can critisize the hp gain when stock 2.8s dyno at 110-115 hp at the wheels. I had 35 rwhp over that and that's 48 at the flywheel...

I will extract another 10 rw horses once I put in a bigger exhaust...I also need to clean my K&N and eliminate the air silencer...

Keep in mind that I did not raise the compression and use 87 octane gasoline.

I should have rephrased my previous post, it seems most 2.8 to 3.4 transplants don't gain as much as I thought, but coming from a V8 background I should realize that there's 2 less cylinders in a V6 to pull power out of. Not knocking your effort by any means, and apologize if it came out that way.

It looks like you're using a manual trans. I think that the loss through a FWD manual is less than 10%.
Think about it. The traditional 15% driveline loss figure comes from a manual transmission longitudinal car. That driveline has approximately 10 bearings, 2 spur gear power transfers and one hypoid bevel gear transfer which is not terribly efficient.

A transverse manual, like the Getrag, has two spur gear transfers, only 6 bearings, and zero hypoid bevel transfers.

There's no way that a Getrag (or Isuzu) has the same loss as a T56 and differential.

quote Originally posted by Will: It looks like you're using a manual trans. I think that the loss through a FWD manual is less than 10%. Think about it. The traditional 15% driveline loss figure comes from a manual transmission longitudinal car. That driveline has approximately 10 bearings, 2 spur gear power transfers and one hypoid bevel gear transfer which is not terribly efficient. A transverse manual, like the Getrag, has two spur gear transfers, only 6 bearings, and zero hypoid bevel transfers. There's no way that a Getrag (or Isuzu) has the same loss as a T56 and differential.

maybe in a brand new transmission and some GM syncromesh lube but not one with 124K and a worn 4th gear syncro.

I would also like to state that tolerances are going to be alot stricter when creating a 6 speed rwd transmission for cars rolling off the assembly line putting 300hp to the wheels than a fwd style econobox transmission with 115rwhp.

In the end frictional losses are all about the quality and condition of your parts.

Let's forget that for a moment... I stated that with bad timing and exhaust coming out freely from the EGR that my car gained 9 hp... with good timing and the EGR back on I gained almost 12 rwhp... The only reason I didn't dyno the good timing with the EGR off is because I had been there for over 2 hours and we had done 12 runs already. This was costing me money and it was time to go. In another month I hope to have a better exhaust setup. I also discover a shaky spark plug wire that I have since replace that also caused alot of the bad runs that I had from runs 6-11.

So in a month or so I will dyno my car again and ABSOLUTELY expext to see over 160rwhp from 207 cubic inches with 90+k miles and a transmision with over 125k miles on it and I will be VERY PLEASED.

I also would like to point out that the typical 3.4 conversion has only averaged 138 hp barring my 2 of 146.3 and 149.8 so I must be doing something right...

Also 160rwhp*350cu/207cu = 270rwhp if I had a v8 so I think I will be producing the appropiate hp given my engine's size. And that's if your engine is an LT4.

quote Originally posted by lou_dias: For run 3 I unbolted the EGR and mounted an L-shaped 3" exhaust pipe over the open egr... this resulted in a 8 hp gain and a few ft*lbs of torque.... This tells me that the stock Fiero exhaust system is WAY TO RESTRICTIVE for the 3.4. BTW, I have an exploded muffler so I think a 3.4 needs closer to a 2.5 inch exhaust.

Im confused here, you take off the egr or the "Y" pipe??

DreX

look at the pics I posted links to. The stock exhaust system was used at all times. My cat is internally mostly hollow and my muffler has holes in it. My EGR was already blocked off from throwing exhaust into my intake, however I took the top portion of it off (2 nuts held it on) and placed 3" exhaust pipe over it to angle the exhaust out of my engine compartment. Keep in mind the the hole made by taking off the EGR was only about 1/2" in diameter but provided for a 9 hp gain.

This proves that the stock system while ideal for a 2.8 is far from ideal for a 3.4 motor. The same goes for the stock water separator and air filter setup. Re-read my original post on that situation as well. 15hp gain in the 5000+ rpm range. Loss below that with no air filter.

I believe I have gone a long way to dispelling some myths about 3.4 conversions for our babies... Like "only 10hp over a stock 2.8".

quote Originally posted by lou_dias: I believe I have gone a long way to dispelling some myths about 3.4 conversions for our babies...

Great work, Lou. I think you have, too.

One thing I've wondered for a while is why everybody thinks that "the 2.8 intake is too restrictive for a 3.4" and nobody considers that it might be the exhaust that's too restrictive. The area of each intake runner is about 1.5 square inches. The area of the exhaust manifold (and the Y pipe) is about 1.5 square inches. The motor has a lot more air coming out of it than it does going in and all this air is going into a tube with 1/3 the area of the tubes going in!

You have shown that the exhaust is indeed quite restrictive and you can get real gains by opening it up. You're breaking new ground. Good job, keep it up.

As a brief aside, I'm trying to build a very hot 2.8 for my race car. I put a ton of work into this motor and only got about a 15% gain on the dyno. For what I've done to this motor I should have gotten a gain in the range of 30% - 40%. I think my hp bottleneck is the exhaust so I'm building headers and a whole new exhaust system.

I think the hp bottleneck of the 3.4 is also the exhaust. It sounds like you're working to change this and I look forward to seeing your results. I think 160 hp at the wheels should be well within reach of a good 3.4. You can do it. Post your results with a big "I told you so."

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Doug Chase
'88 Fiero Formula 5-spd (autocrosser)
'88 Fiero GT 5-spd (daily driver)
'85 Fiero GT 5-spd (rally car)

Thanks Doug. My progress will be posted.

almost forgot to mention that I am using the stock 88 PROM as nobody responded to my offer to be a guinea pig for testing so-called "performance" PROMs in another thread from a couple of weeks ago

I believe that the volume of gasses taken in will be larger than the volume of gasses out of the exhaust. Some of the incoming air is consumed by the burning of the fuel.
If they were the same, wouldn't the intake and exhaust valves be the same size?

This is *not* to argue with your results, though. Obviously the numbers speak for themselves.

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Raydar

88 3.4 coupe. A work in progress.

Out of my mind. Back in 30 minutes.

no way! the volume going out is MUCH greater than the volume going in. the reason the intake valve is larger than the exhaust valve is it is much easier to push out the exhaust than it is to suck in the new air. you get more of a power increase by increasing intake than by increasing exhaust. so, being you only have so much room to use, the best you can do is have the intake larger than the exhaust. also, the main reason theres more volume going out is its actually the same air going in & out, it just gets massively heated cuaseing major expansion of the air.

quote Originally posted by lou_dias: Thanks Doug. My progress will be posted.

lou_dias...Any progress?

Can i just say that be taking off the egr it may not be the releif of exhaust restriction that gives you the power increase, but it could be the fact that youll be getting a better air quality on the intake because you're not reburning gases. EGR Saps power cause it puts dead gases into the intake to reduce Nox's.
Just a thought, correct me if im wrong im 19 and learning, well were all learning arent we???