I wanted to put a good discussion in Tech for everyone to mull over. The question stands today...

What driveline properties and strengths allow drivers to achieve and run high RPMs on a constant level?

Basically, what is needed in engine components to make and hold high revs?

This is a discussion about the possibilities of different drivelines. I would appreciate any input and thoughts on the topic.

Heres a good starter: What would be needed to make a 2.8L with an 8k redline?

Fire away!

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#7277 of 46581 built in 1987.

My thoughts are on you Sean and Chris! Come back safe!

I believe there's several factors:

1 - breathing
High RPM engines usually have 4 valves / cylinder and/or forced induction for volumetric efficiency. If you cant get enough air and fuel to produce torque, high RPM's are worthless - no HP.

2 - reciprocating mass
Internal stress is caused by the force required to accelerate the pistons, rods, etc. Less mass=less stress.

3 - valve train inertia
Many OHV engines will suffer from "valve float" at high RPM's because of the long train of heavy components - lifters, pushrods, rockers, valves. OHC is a more direct connection to the valves, requires weaker valve springs to close.

4 - vibration issues
Higher RPM's require better balance and stiffer components.

So, I believe what you need for an 8000 RPM 2.8 is to take a DOHC 3.4 and destroke it to a 2.8. Or, you could get a 2.8 VR6 from a volkswagen.

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88 4cyl auto Fiero, AC, sunroof
"And isn't sanity really just a one-trick pony anyway? I mean all you get is one trick, rational thinking, but when you're good and crazy, oooh, oooh, oooh, the sky is the limit!" - The Tick

Thank you for the reply!!

So, for a racing application, the 3.4 DOHC is a better choice?

What about (de)stroking? How does it effect high RPM applications?

Turbos and superchargers...Good for high rev use?

Open for discussion to all!

Your RPM's and how high you will be able to take them will be determined by the pressure of your valve springs, the more presure they produce, the higher you will be able to take your RPM's. This is because at a certain RPM, not enough pressure on the valve will result in "valve float". But the down side is that the higher the pressure that faster things start to wear on your valve train, ex. camshaft, rockers. That is why DOHC engins can rev so high, they do not have the push rods producing that extra pressure on the valve train, and wear is REDUCED (not eliminated) to a greater degree.
Your second limiting factor is engine stroke, the longer the stroke the more tourque that is able to be produced. But the down side to that would be vibration, the shorter the stoke the less vibration that is created and greater the ablity to hold high RPM's longer without the engine granading itself.

kinda off and on subject.. do our cars come with rev limiters? my tach reads to 9Gs so I cant really remember to not go that high (I have a auto though) I got on it good tonight and it seemed to rev really high before it wanted to shift.
And when does a turbo really push hard? normal acceleration or kickin it in the butt at high rev? what risk do you have reving hard with a turbo? I have one just waiting to go on my car (lack of time and funds) Thanks

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Who ever said working on Fieros wasn't any fun?? They must not of had a rebody!

quote Originally posted by DjDraggin: kinda off and on subject.. do our cars come with rev limiters? my tach reads to 9Gs so I cant really remember to not go that high (I have a auto though) I got on it good tonight and it seemed to rev really high before it wanted to shift. And when does a turbo really push hard? normal acceleration or kickin it in the butt at high rev? what risk do you have reving hard with a turbo? I have one just waiting to go on my car (lack of time and funds) Thanks

Your tach must be way off if you get 9000 rpm with a stock 2.8L Fiero engine. They redline around 6000 rpm and my 87 has a rev limiter at 6000 rpm. But that is a 5 speed.

Here are a couple of replys:

the 3.4 DOHC is definately a better race engine. Sure you could build either one up, but the 3.4 is so much closer already, and it's stock redline is 7000.

Destroking HELPS high rpm use. Why do you think F1 engines are V10s with only 3L displacement? Less rotating mass is the goal.

Turbos can be designed to make the car drive exactly how you want it. You can have it add power throughout the power range (quick spool, lower total flow), or slam you into the back of your seat (large total flow, long spool time), or both (twin turbo with quick spool).

Turbos are always good for high rpm use, but they wear just as much faster when spun faster. You need to have your fuel and spark management dialed in to run boost at high RPM.

To make a stock engine a race, or high rev engine, you need to do a bunch of things:

lighter bottom end
stronger bottom end (might as well rebuild the whole thing)

lighter valve train
stronger valve train (it's got to spin twice as fast as the engine. try solid lifters and associated cams)

new cylinder head (fiero truck engines are not designed to flow as much air as needed higher than 4000 rpm. Get new heads, port them, match them, polish them.

Intake/exhaust manifold (air in = air out+ fuel)

now that your engine is built, you need to make sure you have quality components to control it.

ignition control box
distributor
bigger fuel injectors
fuel pump
water pump
radiator

I could go on, but the point is that you need to be prepared to drop as much money into the 2.8 engine and the rest of the car as you would to buy a new car.

I wanted to do the exact same thing you are but gave up. I'm just going to use my fiero for burnouts and cruising around town. I have plans for a 10k RPM, 22psi turbo, short stroke V6, but it won't be with the 2.8, and probably not the 3.4.

Good luck.

cccharlie - not be be picky but to make a 3.4 TDC into a 2.8 TDC (or regualr pushrod 3.4 into a 2.8) u need the crank from a Chinese (yea, chinese) Buick 2500 SFI crankshaft...its near impossible to find but i'm gonna try to locate one....

as far as destroking goes i think i'm leading the way into the unknown by attempting to destroke my 3.4 TDC...incase u don't know here's my list:

Bottom End:
-2.8 aluminum head crank (have)
-6" 327 Eagle ESP H-beam rods (need to buy, pending more research into 2500 SFI crank)
-stock N* pistons (have, but will not take more than 8500 revs, looking into forged with bigger bore)

Top End:
-96+ heads (need, also looking into larger valves and porting the combustion chamber out for bigger valves)
-91-95 cams (have, supposedly bigger than 96+ cams)
-tunnel ram intake manifold with LT1 throttle body (need to build, also need TB)
-equal length headers (need to build)

it'll end up being 3.1 liters (3097 cc's to be exact) and with 91-95 heads it'll have a static C/R of 9.7:1 and around 7k when the rods start to stretch out and eliminate the quench area the C/R should be around 10.5:1, i don't have any data for the 96+ heads that i'm gonna use, i need to get a pair first then have them cc'ed, compression will be slighty higher i'm guessing about 10.5:1 static and 12.0:1 dynamic. a word about destroking, this is from my local machinist, u want the longest rods possible, and the shortest stroke, but there we be considerably less torque than the original motor had. daily driving with a motor like this will be near impossible (not impossible, just extremely difficult) unless u have the 4.10 4-speed, which sucks because u run out of gear at about ~150 (who needs to go that fast anyway ). i would like to find the 2500 SFI crank and go with custom rods/pistons, but if not its ok, i'll still have a rod/stroke ratio of 2.01:1 which is great for its anti-detonation/knock properties. i don't want to go turbo with it, i'd rather have a 400hp daily driver thats somewhat reliable vs a 700-800hp daily driver that every time i hit the gas breaks...i still need to see if i can bore the cylinder 2mm over (.068") to get a better bore/stroke ratio and help with air getting around the bigger valves, i'm gonna stop into the machine shop this afternoon and talk to the guy for a little bit about some of my options...

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Eric
'87 GT 5-speed Gold/Tan NOW with a 4.10 4-speed
3.1 TDC + other goodies coming summer of '03

-2.8 aluminum head crank, 6" SBC rods, N* pistons (11.5:1), 96+ heads, home built equal lenth headers, custom tunnel ram intake manifold, 24 #/hr injectors, and a 150 shot of N20 :)

First off, this is a very interesting thread.

I'm surprised that nobody has addressed the problem of lubrication. At high RPMs it can become difficult to keep adequate oil available for the oil pump to provide proper lubrication. A lack of oil at high RPM can cause significantly more impressive (and rapid) grenading of engines as well.

I think if I were to opt to build a high RPM 60 degree V6, this is the rout I would take.

I believe the Pontiac Turbo Grand-Prix had a factory forged crank shaft (this is a turbo 3.1). I would try to locate one of those, and have it offset ground to destroke it as much as possible. I would then utilise a GM performance parts aluminum 60 degree V6 block, and bore it out near maximum. Custom forged pistons would be very nice. Custom Titanium rods would also be very nice. Their light weight and high strength would be ideal for a high RPM engine (more than a little pricey though). I think that 3.4 DOHC heads would be the best way to achieve maximum RPM (yes, I realise that this would necessitate the blocking off of lifter bores in the block etc etc). With 4 valve per cylinder heads, there doesn't need to be as much lift as with 2 valve per cylinder heads. This means that the added spring pressure needed for high RPM use will still not be rediculous, and this will add greatly to the longevity of the top end of the motor. Also, from the perspective of power production, 4 valve per cylinder heads are typically much better suited to flowing at high RPMs. I think the Aluminum block would be necessary because the factory block is simply not the most durable design. The addition of 4 bolt mains would certainly keep the bottom end nice and tight during high RPM operation, where I'm not sure I'd trust the iron block. Also, it never hurts to shave 47 lbs out of the assembled engine.

It would probably be wise to use an aluminum flywheel. I'd seriously think about trying to find a fluid filled harmonic balancer....I don't know of anyone that does custom ones, and I'm almost positive that there are none available for this application.

As was already mentioned, the rotating assembly would have to be machined and balanced to very precise specifications to minimise vibration.

This would be a cool project, but I think to build it and have any kind of long term reliability, we would be looking at nearly a $20,000 engine.

Don't forget, the factory computer would probably not be up to the task of managing the engine at 8 thousand RPMs.

-FD

[This message has been edited by Forbidden Doughnut (edited 04-24-2003).]

[This message has been edited by Forbidden Doughnut (edited 04-24-2003).]

Okay. So a true high rev racer will not be streetable? What about something akin to an s2000?

So, basically, to have a good daily driver, weekend warrior, you need to do a turbo 3.4 DOHC (fortified).

What about gearing? What kind of final drive is good for circle track? What kind of gearing will take advantage of a good power-band?

This discussion rocks! Keep it up!

Thanks to all those that replied here.

i just got back from the machine shop, its gonna cost me about $1200 just to get the short block assembled if i supply all the parts (another $1000+ for pistons/rods). he said it would turn to 10k without any problems, i forget the name of the synthetic oil he said i should use, but i won't have any problems....the top end of the motor will be interesting. we talked about Ferrara valve springs that i can have custom made to avoid valve float above 7600 (or whatever stock valve float is), T-belts won't last more than 10-15k miles revving that high and i don't think the T-chain will last much longer than the belt...

as far as gearing is concerned i'm using a 85-86 V6 4-speed case with the M19 (4.10)final drive. 1st and 4th gear are from a MY8, 2nd and 3rd are the same in all 4 speeds. this will let me do about 55+mph in 1st gear, and go pretty damn fast in 4th gear with the N20 pushing me along...

high revver being streetable - yes it streetable but it ain't gonna move until u wind it up to 5k and keep it above there, if u've ever riden or driven an S2000 u'll see they're dogs until it gets up to 6k...so u'r gonna use the clutch more to pull out since u'll have to rev higher to acoid stalling the car...

titanium rods - unless u have $3000 to spend on rods i wouldn't bother, the rods i'm using are $500 (plus i get 8 of them) and they'll handle all the hp and revs my motor is gonna throw at them...

My 3.4L sees 7000rpm in 4th whenever i feel like it and it will cuise happily along at 5500-6500 too. not to mention excellent street manors. dont buy into the dohc turbo crap. all that will do is drain your bank account. it all depends on what your goals are. alot has to do with your engine builder. increasing the clearances that need to be increased and an excellent oiling system. my motor has 55psi at idle and 80psi at 7000rpm. dont bother using the 2.8 anywhere becuase as far as im concerned the whole casting is flawed regarding its oil galleries. that my .02

[This message has been edited by donk316 (edited 04-24-2003).]

So, basically its a moot issue concerning a weekend warrior fiero?

Why not buy into the DOHC Turbo? I have read that if you tweak the turbo correctly, it can give you some great boost all along the power band without being peaky. The DOHC, as stated above, has better air flow capabilities. Hmm...

Can any 3.4L DOHC Turbo owners chime in on this?

This isn't my goal. I am creating discussion where everyone can share experience in this field. Where I am interested in a DOHC 3.4L Turbo project, that will not happen for a very long time.

Give your experiences! SCCA Fiero, Artherd, etc. Let's see what the autox people have to say about their motors' weaknesses and strengths and what they would like in a motor. It is open for discussion.

Thank you all for the replies and input. This discussion wouldnt be good without it!!

Just another angle in this thread.

Why is there so much hype into high-rpms? Of course we don't need another 'cubes vs revs' debate but the article I remember was comparing the S2000 to the Porsche Boxter. Both cars are very similar in all dimensions, with similar peak power, but it seems to be all about the curves (power and torque, that is). They said the Boxter was WAY more streetable, better suited to city driving. They did admit the S2000 was a lot of fun in the open road when you could beat it within an inch of its life. It just seems all that shifting to keep in the powerband is a waste when you could have a much lower powerband. I suppose it depends on trans choice too. Too bad nobody has an easy six-speed swap

Anyway, I just thought I'd add more fuel to the fire and watch it burn.

Very interesting thread though, and for the record I want to go with a high-rpm motor myself

Cheers,

Kris
'87 GT

donk316 - do u have a 3.4 pushrod or twin dual cam? if u'rs is a pushrod and is spinning 7K whenever u want thats rather impressive i guess, i didn't think the pushrod motors like to go over 6500....

I'm tring to make around a 8000rpm redline in a 3.5L DOHC. I'm going to go the route that lambos go with variable intake manifold. keep the low end torque and upper end. I'm also compound turbocharging to give adaquit flow. I'll be going through the engine to beef it up. I'm going for around 350-400hp streetable.

quote Originally posted by coinball: donk316 - do u have a 3.4 pushrod or twin dual cam? if u'rs is a pushrod and is spinning 7K whenever u want thats rather impressive i guess, i didn't think the pushrod motors like to go over 6500....

-Those NASCAR folks do spin over 9000 rpms with pushrod engines whose lineage dates back to the 50's.-

I am building/having built a 2.8 for auto-x. I did not really focus on high RPMs. the redline will probably be about 6500. I did focus a lot on balancing the bottom end. I have factory rods (remanufactured, shotpeened, and with ARP bolts), aluminum pistons .030 over making it a 2.9 (9 or 9.1 : 1 c/r), I had my crank hardened...I got an '88 crank, because I feel like internally balancing an engine takes a little stress off of the main bearings. I have a windage tray from the fiero store, with custom main bolts from ARP. It was torque plate honed, and I am waiting for it to be align honed as well. In my opinion, this was the best choice for a budget racer, I focused on reliability more than maximum power, and I didn't focus much on high RPMs because I don't feel the engine design of the 2.8 is really up to it, and regardless, high RPMs = shorter life expectancy. I am seriously considering a turbo later on though to give it a little extra kick.

So that is pretty much where I stand on the issue of building a pushrod 2.8. I would have liked custom rods, and custom forged pistons, and a few other little goodies...but lets face it, I was in college when I started this project, and I was lucky to be doing it at all.

-FD

quote Originally posted by Kris Duck: Just another angle in this thread. Why is there so much hype into high-rpms? Of course we don't need another 'cubes vs revs' debate but the article I remember was comparing the S2000 to the Porsche Boxter. Both cars are very similar in all dimensions, with similar peak power, but it seems to be all about the curves (power and torque, that is). They said the Boxter was WAY more streetable, better suited to city driving. They did admit the S2000 was a lot of fun in the open road when you could beat it within an inch of its life. It just seems all that shifting to keep in the powerband is a waste when you could have a much lower powerband. I suppose it depends on trans choice too. Too bad nobody has an easy six-speed swap

The cubes/revs debate really stems from how you react to the car as a driver. My honda has no torque, and only has real power from 5000-6500 rpm. This is what I like. I get 40 mpg when I keep it under 3000, which is daily driving. If I want to move I'll rev it up. This is how I like an engine, personally, good mileage in the low end, with a peak output in the high end.

Most people (americans, although I am also) like off the line torque, which throws you back into your seat. The problem with this is that american motor companies build large engines that are designed with low tolerance parts that aren't expected to see high performance. Most people are satisfied with this, but I can live with the lack of torque in the bottom end of the RPM range.

For this reason most tuners start with foreign engines, which are designed for higher loads, because they're usually smaller. If I had my way I'd get a nissan engine, either the SR20 series or the engine from the 300zx.

First, there is no need to destroke anything to turn up the RPMs. The 2.8 only has a 2.99" stroke! The 3.4 DOHC has a higher redline (7k) and a longer stroke (3.31"). The small block Chevys that the NASCAR guys are turning 8000 RPM have a 3.48" stroke. Many years ago Dad and I built an alcohol burning 383 for a stock car and this thing would turn 7200 RPM all day long with a 3.75" stroke.

The 2.8 bottom end is quite capable of handling 7000 RPM if prepared properly.

As for gearing on a circle track, you want a gear that will let you come off of the corner in the power band, and not run out of power before you have to lift for the next corner. That's all there is to it. You won't be shifting and your RPMs probably won't vary more than a couple thousand RPM around the whole track.

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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)
'87 Fiero SE V6 5-spd (for sale $2200)
'88 Fiero Formula 5-spd (parts car / future rally car #2)
Custom roll cage fabrication available
Custom exhaust fabrication available

The first thing that usually goes on these engines when you overrev them is the crankshaft. I'd say for that kinda rpm you'd need a crossdrilled and forged crank. Also, a high volume oil pump is a must. Plan on doing this to the 2.8 before you even think of modding anything else.

Phil

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87 FIERO GT 2.8 5spd
0-60 in 6.8 seconds!

doug - the reason i'm destroking my motor is for the longer rod/stroke ratio which inturn lets me run more compression and advanced timing without having any detonation issues (or less than an equal motor with a lower rod/stroke ratio). plus by boing it .060" over i can put bigger valves into the TDC heads and not worry about flow restrictions from the cylinder walls being too close...

doughnut - "those NASCAR folks" also have solid lifters.....i don't think donk316 has solid lifters (or if anyone makes them for the 60* V6 family....), just a thought, there is a limit to hydralic lifters (or so i've heard)

quote Originally posted by coinball: doug - the reason i'm destroking my motor...

No worries, I think what you're doing is cool. My comment wasn't directed at you, it was directed at everybody who said that motors need to be destroked to turn up the RPMs.

quote i don't think donk316 has solid lifters (or if anyone makes them for the 60* V6 family....)

They make them. I have them in the race motor in my rally car.

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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)
'87 Fiero SE V6 5-spd (for sale $2200)
'88 Fiero Formula 5-spd (parts car / future rally car #2)
Custom roll cage fabrication available
Custom exhaust fabrication available

doug - check you PM's

Dont blast me if its already up there, I didn't read the whole thread yet, but if you wanted a high reving motor wouldn't the quad four be a good choice? I hear that a turbo'd quad four is pretty quick and spins pretty fast stock.

quote Originally posted by fieroman84: Dont blast me if its already up there, I didn't read the whole thread yet, but if you wanted a high reving motor wouldn't the quad four be a good choice? I hear that a turbo'd quad four is pretty quick and spins pretty fast stock.

Actually there is a turbo quad four in the May hotrod magazine that is pushing 625 horse, and 500 ft/lbs (page 76 if anyone is curious).

-FD

quote Originally posted by coinball: donk316 - do u have a 3.4 pushrod or twin dual cam? if u'rs is a pushrod and is spinning 7K whenever u want thats rather impressive i guess, i didn't think the pushrod motors like to go over 6500....

man you need to get out more. Back in the day it was common to see an SBC revvin to 7,000. theres even SBCs that have a 13,500 redline. Hell our 496ci Big Block in our chevelle happily revs to 7,500

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--Adam--
1987 Blue GT 5-speed
IM AOL: FieroGT5speed
16 years old and already selling my stuff to pay for repairs to my Fiero...which i sold my stuff to buy in the first place