Don Kraus's 427 LSX Update (Page 4/28)
Dennis LaGrua JUN 09, 10:15 AM
That's one mighty large engine to be installing in a Fiero! It then gets us to an important question of how much horsepower the stock Fiero frame can tolerate and how much reliability will result. I am assuming that you are reinforcing the frame. Nice job and good luck with the project.

------------------
87GT - 3800SC Series III engine, 3.4" Pulley Flotech Exhaust Autolite 104's 4T65eHD
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

Capt Fiero JUN 10, 12:09 AM
Edited because I think my brain was fatigued when I typed it up the first time.

Hey Dennis, I think you brought up a good point on this. Just how much Power/Torque can a Fiero handle. Hypothetically, say you have a bullet proof trans/engine with solid mounts. Ed Parks has found the 88 Cradle will twist badly with just 300lbs of torque, so it needs to be re-enforced, Blair has found that with a 3800SC on an 85 Cradle it should be re-enforced. I found that with repeated abuse on my V8 with the dog bone relocated to the drivers side, it started to crack the frame at the strut tower, and I believe 2 or 3 other cars, both SBC and 4.9 have had similar problems. I know that my suspension crack in the front was again due to repeated abuse, I would go blasting down side roads at WOT and end up hitting a chuck hole hard and eventually broke the upper shock mount. (never bent a rim or blew a tire)

In my personal opinion, the next place we are going to start to see breaking parts, will be the front (forward) side of the cradle where it mounts to the car is will start to show signs of metal fatigue. The rear of the cradle is being pressed into the body on hard launches however those two front cradle bolts are the only 2 bolts holding the entire front of the engine and trans in place. All the load DOWN is being carried by them. They are pretty heavy, but the "sheer force" and strain must be getting to them. I am not talking about just the physical bolts, but the mounts and brackets that the bolts go through.

If 300lbs of torque with constant abuse will break these parts, I could to say 600lbs of torque is going to have them apart in several less passes down the track.

[This message has been edited by Capt Fiero (edited 06-10-2008).]

Dennis LaGrua JUN 10, 12:06 PM

quote
Originally posted by Capt Fiero:

Hey Dennis, I think you brought up a good point on this. Just how much Power/Torque can a Fiero handle. Hypothetically, say you have a bullet proof trans/engine with solid mounts. Ed Parks has found the 88 Cradle will twist badly with just 300lbs of torque, so it needs to be re-enforced, Blair has found that with a 3800SC on an 85 Cradle it should be enforced. I found that with repeated abuse on my V8 with the dog bone relocated to the drivers side, it started to crack the frame at the strut tower, and I believe 2 or 3 other cars, both SBC and 4.9 have had similar problems. I know that my suspension brake in the front was again due to repeated abuse, I would go blasting down side roads WOT and end up hitting a chuck hole hard and eventually broke the upper shock mount. (never bent a rim or blew a tire) Just the repeated WOT throttle and then breaking hard.

In my personal opinion, the next place we are going to start to see breaking parts, will be the head (forward) side of the cradle where it mounts to the car is starting to show signs of metal fatigue. The rear of the cradle is being pressed into the body however on hard launch those to front cradle bolts are the only 2 bolts, holding the entire front of the engine and trans in place. All the load DOWN is being carried by them. They are pretty heavy, but the "sheer force" and strain must be getting to them.

If 300lbs of torque with constant abuse will break these parts, I could to say 600lbs of torque is going to have them apart in several less passes down the track.



Perhaps this is an illustration of the point that when you change one thing it often affects another. I've always maintained that any drivetrain should be designed as a complete system. Don seems like a guy who understands how to build fast Fieros and I would assume that he is taking steps to reinforce the cradle and the attachment points- not really hard when you think about it as its just a matter of additional metal being welded here and there. Don wants to go where no Fiero owner has gone before and I don't doubt that he will succeed.
I would not discount the 300 ft lb max figure given by Ed Parks. Eds been working on Fieros longer than just about anyone and he's seen it all.

------------------
87GT - 3800SC Series III engine, 3.4" Pulley Flotech Exhaust Autolite 104's 4T65eHD
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

jscott1 JUN 10, 12:16 PM
Bolts are a lot stronger than you give them credit. 300 ft-lbs is not a lot for a bolt designed for 100,000 lbs per square inch.

Usually a stress failure will occur where you have compromised the structure. Like if chunks are taken out of the frame and it's not reinforced.

I would be very surprised if 300 ft-lbs alone would damage a stock cradle. Of couse you pile on other abuse like hiiting chuckholed at WOT you can break something.
Don Kraus JUN 10, 05:00 PM
Hey Guys,I have reinforced and boxed in the engine cradle,touched up welds where needed.I am using 5 motor mounts,big one in back and two on each side all with poly to give the engine and transaxle some flex.I don't believe solid mounts are good because they don't give the system any breathing room.I drove my Aldino and dragraced it for eight years,doing wheelies on just about every run and never cracked or bent anything.This car will weight about 200 lbs less than the Aldino and that will make it easier on the drive train.Also,its an automatic and that has some give in it to help keep things together.If you took that same engine and put a manual trans.behind it,put sticky tires on it,reved it up and poped the clutch I'll guaranty you something eventually would break somewhere.I like to give my equipment as much shock relief as I can so I don't break things.
Time to get back at it,thanks for all the attention and comments.
Don

------------------
Too Far
60' - 1.491 sec
1/4 mi - 11.323 sec
mph - 116.40

PURPLE REIGN JUN 10, 08:50 PM

quote
Originally posted by Don Kraus:

Here's and update for everyone on the 427 LSX project with a buildt 4T65E transaxle with 3:69 gears.And no Shawn my cars don't blow up like yours,thats why it takes a little longer to build it right the first time. Blah blah blah




WOW ............that's an intersting way to open a thread and reveal your childish ignorance.

If your brain was as big as your mouth you'd figure out that [color =red] ANY [/color] built car will have problems. I guarantee you any wager, that you'll have issues. But then again if you spent less time lipping off & badmouthing other people behind thier back you'd finish more than one project every 6 years.

Mine had issues due to the horses-ass engine builder.............nothing else. Interesting how every piece of " know-it-all " advice was WRONG.

Have you run out of checks yet getting everyone to build that for you ?
Racing_Master JUN 10, 09:15 PM

quote
Originally posted by Don Kraus:

I don't believe solid mounts are good because they don't give the system any breathing room.




Well... I believe in solid mounts because of their principal

Everyone knows, at least I hope, Energy cannot be created or destroyed, only converted. Energy used to compress the rubber or poly mounts is converted, SO, in essence, you lose some power from the poly or rubber mounts. Solids make it so it has to twist the whole car. Problem is that you cannot (I repeat, CANNOT) place ALL solid mounts on an engine and transmission. The engine will twist the chassis, I dont care how well you build it, it will twist it, and if the trannie mount is also solid, at least on longitudinal, it will break the bellhousing off the transmission. Also if you use solid mounts, I can bet it wont be a good car to ride as a daily driver, rattle your bones out all over the place. Can-Am cars used the engines as part of the frame, actually one of my ideas for a Fiero custom frame is having the engine an integral part. Generally speaking, this will make it so 99% of the force produced in the engine gets to the rear wheels. Though it be a miniscule amount that using solids over rubber gives you (probably a fraction of a HP) every hp counts in racing.

By the way, nice lookin car! Should be awesome when its done
madcurl JUN 10, 09:20 PM
Any additional close-up pics of the brakes?
Don Kraus JUN 10, 10:15 PM
Shawn,looks like you can hand it out but can't take it,pretty childish.The reason I posted that was because you asked in the other thread if I blew it up yet.I was just replying to your statement from the thread of an update on my car.The rest of your statements don't make sense.I don't know why you are so bitter.

Madcurl,I'll get some pictures of the brakes and mounts for you.

Don




------------------
Too Far
60' - 1.491 sec
1/4 mi - 11.323 sec
mph - 116.40

IMSA GT JUN 10, 10:19 PM
HOPEFULLY, this thread does not turn into a war over the motor issue....Keep the updates coming