dyno dissapointment 3.4 iron head

[merlot566jka]

well its been awhile since ive posted a new topic here....

ive recently put a new iron head 3.4 in my fiero. ive had 2 other 3.4s in the car and all had bearing failures. well the new one seems great on the bottom end. when building this engine, my machinist said my extreme ported heads werent going to make any power till the higher (8000 rpm range) rpms. so i said screw it, ill use a seat of stock iron heads and stock lower manifold. I figured i wouldnt see any reall loss. well after getting the 7730 ecm in and working, i got it tuned on the dyno. 151hp and 190trq at around 4400 for the hp and 3900 for the torque. very dissapointing. heres what the engine has done to it

3.4 iron head block, zero decked, knife edged crank weights bored .020 over
3.4 iron head pistons
3400 windage tray
stock cast iron heads
crane 99846 h-11 tool steel valve springs installed at 1.75inch (135lbs seat pressure and 383lbs open at 1.2'')
crane 272 cam
comp 1.6 roller tip rockers
sivalves.com stainless valves, stock dia
heads milled .010
3.4 lower intake manifold
trueleo upper intake manifold
03 4.6l mustang throttle body
mustang tps
electromotive iac adaptor
trueleo headers and ypipe
2.5 inch exhaust, flowtech afterburner camaro style muff
24lb injectors
7730 ecm conversion, using $88 code mask
dis set up
delco (oem heat range) spark plugs
modified crx intake tube
160 thermo, ecm fan on at 195, off at 185

durring the tuning, the tuner added more fuel, got the blms close to 128 and the a/f ratio close to 12.5 at wot. then he added some more advance at wot. but stopped there and told me ''it is what it is buddy''. he was pissed he even had to dyno tune it, hes a big corvette guy and made fun of the car the whole time i had it in his shop. looking at the big picture of performance cars, i know the fiero is no corvette and its barely a sports car, but, damnit, i like it and its fun for me. why try to take that away from me?!

back to the point, these numbers are retarded low. this was on a dyno jet and i have the 5spd getrag. im thinking 3500 heads and up. i have tons of questions that havent been answered in all the 3500 posts, but ill make a seperate thread for those.

the plus side is, i drove this car from virginia to oklahoma the day i got it tuned. (24 hrs of driving, with only stopping for gas and food) and got an avg of 30mpg. this is phenomonal in my opinion.
but a bigger look at it, i have the equivlant to a torquey 4banger....good gas milage and no hp to boot. what did i do wrong? did i kill my self on the heads? not a big enough cam? trueleo not as good as it apears? power just falls off before i reach 5000rpm, almost like i am trying to feed this thing through a soda straw. the tb is plenty big enough, the filter is more than adequate, yet i feel the problem is the ancient heads and intake setup. am i close on my guestamation?

[ForcedFirebird]

You hit the nail on the head (pun intended). I haven't heard too many good things about the Trueleo intake either.

You can do like I am and slap a 3500 top end on there. I have many posts on my progress, and am definately going to dyno it to fine tune once it's running. With 3500 heads and a little chamber modification, you can have less than 11:1SCR with the 3.4 8cc dished pistons.

My block will be here on Thurs, once the rebuild is done I will check for valve clearance. SuperDave just dyno'd his 3500 with a port job and huge cam giving him over 270hp to the wheels.

I don't care what people say - porting the iron heads is a good thing, and a 5 angle valve job will help, but you are still limited by the design that was inteded for fuel mileage.

[merlot566jka]

fuel miliage checked out ok with those heads. the valve job is a 5 angle on the heads, still sux tho!

what kind of chamber work are you doing? whats the skinny on porting the 3500 heads? every one seems all hush hush on these heads, as if they are holding dimonds in the ports... cmon now, these arent top secret copo heads here, theyre production v6 heads, holding out on porting info is holding back the 660 movement.

[ForcedFirebird]

http://60degreev6.com/showthread.php?t=38136

No secrets, it's just easy to overport them.

[bszopi]

Did you drive to Tulsa and goto FastChip to have it tuned? I feel sorry for you if you did. I had him reflash my OBD1.5 setup a few years back. After a couple days of not being impressed with the tune, I took it back to him to reflash to original and got my money back.

[Superdave]

Airflow is directly proportional to horsepower, the 3500 top end will do wonders for your setup.

It is easy to mess up the 3500 heads, they don't need that much porting at all.. maybe just clean up the very few casting marks and sand out the exhaust ports.

[merlot566jka]

i had the car tuned in virginia at automotive technologies. the guy who tuned them is master ase certified and a huge gm tuner...he knows his stuff...but his stuff wasnt a fieo with a 3.4 and a 7730 ecm....

[bszopi]

Ok, so you live in OK then. Howdy neighbor!

[merlot566jka]

howdy, lol. just drove through your state... not going to lie, i was bored

[Joseph Upson]

I've mentioned on the Fiero forum at least twice to date that it's time for members that are still favoring the 60 degree V6 to stop building rear wheel drive 3.4L engines and leave the cast iron head ages for the fwd aluminum head engines.

Unfortunately you have already done the work and very, very likely spent the cost of a fwd 3400 swap only to fall far short of its stock rating. I wouldn't even bother retrofitting an aluminum head intake system on it since the Fiero calls for a front wheel drive block. Sell what you have in parts to get a large part of your investment back, buy a 3500 and go to work. The 60 degree store has everything you need as far as adaptors and since your car is already wired for DIS ignition you are that much closer to a near drop in swap.

Not only do you get the power and efficiency benefit of the aluminum heads, they'll shave 30 lbs off the top of your engine.

And if you really want to carry a big stick quietly, ignore Super Dave's comment in his ride description and put a turbo on it. You "won't" need no stinkin V8 that's for sure.

[2.8RS]

The 3x00 top end will help you out alot.

[merlot566jka]

well here is the issue joseph... like youve stated, i dumped time, money and a lot of hearache into this car. going to the full 3500 is a little more than i want to handle at the moment. this is the 4th engine this car has seen in 1 year. ill try with a retro-fitting of the 3500 heads on my motor. the cam will make up for the extra compression and the compression would help add to the gas milage (not saying that is even a real factor here). the other factor is this short block was built really well and things couldnt be better with the lower end. going to the full 3500 means i have to do a whole host of changes to the ecm, set things up for all the crazy oddities that the 3500 holds. just swapping the heads and manifolds alows me to keep the engine in the car....if i have to drop the cradle again im going to blow a gasket!!! not that its hard, but its such a pain in the ass and im sick of it!
selling the parts may be a little tricky, the fiero crowd is usually younger, unwilling to fork over cash, and looking for the newest ricer mod for thier car. ive got $165 for the valve springs, $150 in maching of the heads, $140 in valves, $600 in the intake and who knows how much in all the small stuff ive had to change. just trying to mark stuff down 15% and selling it on fiero .nl will take me forever and several markdowns just to sell. once i get my 3500 parts ill give a stab at selling that shit.

[merlot566jka]

[Guest]

stock heads are barely good enough for a 2.8. Put your ported heads on and redyno and retune. I mean you couldnt' have hogged out that much of the heasd could you have?

I don't think thats too easy to do. You got any flow numbers on your ported heads?

Your motor can't breath with those tiny head ports. Thats your prob, not the intake or anything else.

I dynoed my old 3.4 and with very mild headwork, an unknown cam(though larger then stock) 52mm tb and all stock fiero intake, with sprint exh manifolds, I put down 149 whp and 190 tq untuned on a stock 2.8 chip through a getrag 5 spd.

You already have the 7730 ecm swap. Pull that iron motor out, sell it for like $1k or so, and put in a 3400. it will drop right in, adn with some head and cam work will get you 210 ish hp at the wheels no problem.

Or keep what you have and put a turbo on it. My same motor on 7 lbs made 210 whp and 270 ish tq non intercooled and untuned. Not super quick, but a low 14 sec car easy. Its now at 11 psi and some nitrous with an a/a intercooler on it.

[Superdave]

And if you really want to carry a big stick quietly, ignore Super Dave's comment in his ride description and put a turbo on it. You "won't" need no stinkin V8 that's for sure.