Yo kid when did you get pics of your cars progress? And why have you not been sharing? and on a side note did you ever get my pics transfered to the CD I gave you?, car shows will be starting in a month or so, looking forward to attending them with the Targa this year, hope it dosen't all summer like last year.
Every wonder why a 206 vette is just about as fast as the Ferrari 360?
Pushrod engines make gobs of low end torgue, where as DOHC needs high RPM's to make its power.
Its not the pushrods that make the low end torque on Vipers and Vettes, its the larger displacement. The DOHC head design is superior to a pushrod design in airflow , hence it makes more horsepower for any given engine displacement. The DOHC is a true "hemi head" design with cross flow, IE the intake is on one side, the exhaust on the other. It's much more costly to manufacture, and more difficult to service because of the greater number of parts mostly. Japanese crotch rocket motorcycles (and Indy cars and formula I cars) all use DOHC and a hemispheriscal head design to produce more power at a higher RPM than a pushrod engine could ever possibly spin.
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11:31 PM
Exotic Rida Member
Posts: 563 From: new orleans louisiana, now displaced to atlanta Registered: Jan 2004
will having a DOHC engine change the so called personality of the car?? i dont think so i drove both a vette and a ferrari f355 both were 6 speeds and the f355 instantly put me in my seat tere was no so called waiting until the revs get high only i let off the clutch and hit the gas and the car took off!! whooooooooooooooooooooo !!
now as the vette it did the same thing took off as soon as i hit the gas!!!!
would it be a crime to put lets say a 4.5 liter DOHC v8engine in a vette that turns 8500 rpm with 500 hp and 300 torque? 100 more hp but 100 less torque, is that basically the same power as a 6 liter turning 400 hp and 400 ft/lbs of torque???
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11:47 PM
Mar 18th, 2004
Fastback 86 Member
Posts: 7849 From: Los Angeles, CA Registered: Sep 2003
Well when you get up into the big numbers, any engine is going to throw you back into the seat. Any motor with several hundred horsepower and torque is gonna go like hell. When you get down to the lower numbers, like a pushrod 3.4 vs a 3.4 DOHC, its 160HP vs 230HP or so. I forget the exact numbers, but the torques are something like 180 and 205 respectively I think. The DOHC doesn't have much more than the pushrod. The big deal is where in the powerband it is. The pushrod will initially throw you back harder, but the DOHC will keep going much longer and have much more power in the higher RPMs. At the lower HP and torque numbers, you have to make a trade off of initial kick in the pants to high RPM screaming. When you're playing with Vettes and Ferrari's, they've got so much power either way that the trade off becomes much less significant.
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12:02 AM
Golden86 Member
Posts: 1191 From: Glen Ellyn IL Registered: Jan 2004
Every wonder why a 206 vette is just about as fast as the Ferrari 360?
Pushrod engines make gobs of low end torgue, where as DOHC needs high RPM's to make its power.
I would not say one is better than the other. They both have advantages. American car makers tend to stay with the pavement pounding torque monsters. We like it that way. It's kinda a muscle head thing.
BTW - we do have a the technology. Look at the Cobra mustang, our 3.4 DOHC, Northstar, Quad4, and so on. It is just that our mustle cars tend to remain just that.
This about sums it up. Small displacement OHC engines turn some mega rpms compared to pushrod. Typical stock Porsches and Ferraris are good for up to 10,000 rpms. Some of like the formula engines turn over 15,000. By eliminating pushrods, you practicly eliminate any valve float. On long tracks, lite OHC, high reving engine is best. On one with lots of tight turns, you want low end power, but you can use the gears in the OHC to keep the revs high enough to keep up pretty well. Pontiac back in the muscle car days had a problem with high revving resulting in lots of bent pushrods.
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09:25 AM
PFF
System Bot
OH10fiero Member
Posts: 1541 From: struther OH Registered: Jun 2002
For the sake of discussion, trashed Mercury Marine ZR1 motor ->50,000 to replace; Low Mile used ZR1 complete car ->50,000 Not all cars will end up on this end of the spectrum, but the LT1 powered vettes win hands down in the repair world even if the had their headlights handed to them on a platter by the ZR1.
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05:04 PM
TaurusThug Member
Posts: 4271 From: Simpsonville, SC Registered: Aug 2003
on the push rod vs DOHC topic i would rather have DOHC as long as its done like my taurus was. my 98 Taursu SE had a 3.0 Liter Duratec 24-valve DOHC v6 rated at 200 HP and 200 lb ft, my Fiero is rated at 140 hp and 170 lbft. even though the taurus weighed between 3500-3700 lbs(closer to 3700, all options) and FWD it would have stomped the living crap out of my fiero ANY DAY. the only disadvantage to the taurus was that there wasnt a lot of fun down low but once you got above 3000 rpm there was a big jump in power and it pulled untill its 6500 rpm redline, and a little after it too(8000 rpm sounds cool in a taurus :rolleyes i know that the abuse that my fiero has gone through doesnt help with its power as well as the fact that its 80's gm technologie(or lack there of) but why did that 3.0 make so much more power and torque than my 2.8?
The sad thing is that the ZR1 vettes were just slightly faster than the LT1 versions in the 1/4 mile. But then again, Lambo's and Ferrari's are pretty slow comparitively speaking in the 1/4 mile too. It is the all-out top end speed where these engines really shine.
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09:40 PM
fst4rsc Member
Posts: 98 From: Farmington, NM Registered: Oct 2003
I may have got in on this late but I have heard what -may- be coming down the line from on of our GM ASEP instructors at SJC: A 42 Volt selenoid valve engine. So with this system, the valve is lifted electronically. You get infinite valve adjustment controlled by computer according to RPM. At low rpm the valve lift is low and at high rpm, it is increased. The entire cam/rocker setup would be eliminated. I thought that sounded like a cool idea. Hope it works out.
i know that the abuse that my fiero has gone through doesnt help with its power as well as the fact that its 80's gm technologie(or lack there of) but why did that 3.0 make so much more power and torque than my 2.8?
