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View Full Version : How much power can a Pre-Common Block handle?



tvanlant
03-21-2006, 01:02 AM
I was considering switching to a common block in my 87 GLHS since I have the engine out. But with a little more research, its going to cost more than I really wanted to spend to do the swap. Thedodgegarage says that the pre-common block starts to flex at 250 hp. I don't know what hp levels I'm at, but I will give a list of modifications so you can get an idea. Keep in mind that this car is my daily driver and gets run at full throttle daily, and is taken and beaten hard at the track on weekends.

With that said, let me know your opinion on the pre-CB and/or if you know of others who have had success/failure with the pre-block.

Shortened list of modifications:

Forged Venolia Pistons
T2 Rods
Ported 782 Head
'88 Roller Cam
stock turbo w/ .63 Exhaust Housing @ 20 PSI
Treadstone intercooler w/ Spearco core
52mm Throttle body
+20% Injectors
255 lph fuel pump, AFPR
MP Stage II logic Module
free flowing exhaust
A555 transmission, beefed up
BF Goodrich Drag Radials

turbovanmanČ
03-21-2006, 01:58 PM
With the stock turbo, you'll make around 250 whp, so you'll be fine. If you plan on going with a bigger turbo and more power, you might want to consider upgrading to a CB but many others have used Non-CB's at higher levels and done ok.

tvanlant
03-23-2006, 04:34 PM
Any other opinions? I see on TD.com that Bryan is running 34 psi and 11s on a pre-common block.

tvanlant
03-23-2006, 04:37 PM
This is a quote from Gary Donovan's site:
"A common block is a must for any engine making over 250 hp for any length o time otherwise broken main caps or crankshaft will be the result."

The thing that worries me is "for any length of time." Since it is my DD.

GLHSKEN
03-23-2006, 05:26 PM
Haven't answered because I answered you in another thread. Bryans car is NOT a dd. It is a strip beast. Gary's advice is for safety.

"Top Fuel" Bender
03-24-2006, 12:15 AM
Not to curse myself but I 've had my '85 block at 300+ Bhp for 8+ years now
Just in the past year have I've been experiencing head lift problems
I am running a forged crank and arp stud everything with a lot of luck
And definetly not a daily driver
If / When I do it over again I'll have a CB w/ a non forged crank
If you got the motor out and plan on keeping it switch over

Lugert
03-27-2006, 02:46 AM
My car was a Daily driver until I put the new motor in it.

When running the STOCK Long Block from valve cover to oil pan:
337 whp, 34 psi and mid 11's, Street Legal, Registered and Insured with Current Plates.
(The 11.52 times were with Slicks)

Add Big Turbo, Big Intercooler and Lots of fuel.

Not too many people running around with Cast pistons at that level.

I do not see a need to go to a common block if you are going to keep it under 300 whp.

BadAssPerformance
03-27-2006, 09:35 AM
Keep in mind vehicle weight as well. An engine/drivetrain making 250HP will work less pulling a lighter vehicle...

johnl
03-27-2006, 12:19 PM
My car was a Daily driver until I put the new motor in it.

When running the STOCK Long Block from valve cover to oil pan:
337 whp, 34 psi and mid 11's, Street Legal, Registered and Insured with Current Plates.
(The 11.52 times were with Slicks)

Add Big Turbo, Big Intercooler and Lots of fuel.

Not too many people running around with Cast pistons at that level.

I do not see a need to go to a common block if you are going to keep it under 300 whp.

Bryan - love the cast pistons part - looked at your Shadow pic/description. Nice. Could you please post some pics of your frame ties/reinforcement?

looneytuner
03-27-2006, 03:11 PM
There is an engine recycler in North St. Louis (Wellston) where you can pick up a cb for about $50. They tear down engines for crappy engine rebuilders (jasper and Shreves) If your starting from scratch, Why not go better. Looking at the two different blocks side by side, you can see the dif.

tvanlant
03-27-2006, 08:11 PM
I'll have to look into that if my pre-CB fails, but for now, I'm going to give it a shot. Whats the worst that could happen? (as long as the destructo doesn't hurt my pisons).

cordes
03-27-2006, 08:15 PM
I'll have to look into that if my pre-CB fails, but for now, I'm going to give it a shot. Whats the worst that could happen? (as long as the destructo doesn't hurt my pisons).

I am in pretty much the same boat as you are. I plan on putting out over 300WHP, so you wont be the only one hoping to keep things together.

Lugert
03-28-2006, 01:02 AM
Bryan - love the cast pistons part - looked at your Shadow pic/description. Nice. Could you please post some pics of your frame ties/reinforcement?
I would be more than happy to post pictures of the frame ties and cage.
I should be getting the car out of storage this weekend.

-Bryan

8valves
03-28-2006, 01:15 AM
I would be more than happy to post pictures of the frame ties and cage.
I should be getting the car out of storage this weekend.

-Bryan

I thought you sold your car?

Aaron Miller

Lugert
03-28-2006, 01:27 AM
I thought you sold your car?

Aaron Miller

Nope. Still here in the garage tucked away.

Hopefully soon I will have enough time to work on it.

Been busy with the vinyl making. I am sponsoring 4 race cars this year so far, I think I have one more in the works, but time will tell on that one. :)

johnl
03-28-2006, 01:57 AM
I would be more than happy to post pictures of the frame ties and cage.
I should be getting the car out of storage this weekend.

-Bryan

Thanks, I'll be waiting.

tvanlant
02-11-2007, 01:06 AM
Its been a while and just to follow up on this thread so maybe future readers with the same questions will know....

I have been running my pre-common block engine for 10 months now and its still holding up. I used the stock cast crank and ARP main studs. It's daily driven and see multiple WOT 20 psi passes each day, and has seen several 12 second passes.
Super 70 will be coming soon, so we'll see how it holds up to that.

mo' parts
02-11-2007, 01:49 PM
Its been a while and just to follow up on this thread so maybe future readers with the same questions will know....

I have been running my pre-common block engine for 10 months now and its still holding up. I used the stock cast crank and ARP main studs. It's daily driven and see multiple WOT 20 psi passes each day, and has seen several 12 second passes.
Super 70 will be coming soon, so we'll see how it holds up to that.

was this with the stock garret? i would be happy to see some 12's with my omni and set-up in sig:thumb:

tvanlant
02-11-2007, 02:05 PM
How in the world did you ever fit a TBI header in your omni?
That is with the stock turbo (110K miles) but with a .63 exhaust housing bolted on. That is also with BFG T/As. The turbo is huffin pretty hard to supply what the head can flow, though. After a full run, the hot side intercooler pipe is almost too hot to touch!

BadAssPerformance
02-11-2007, 03:19 PM
was this with the stock garret? i would be happy to see some 12's with my omni and set-up in sig:thumb:

Should be able to do it with an Omni for sure.

Stock Garret, '87 T1 short block, and mostly stock everything else got my full weight Shadow in the 12's

http://www.turbo-mopar.com/forums/showthread.php?t=7538

contraption22
02-11-2007, 03:43 PM
How in the world did you ever fit a TBI header in your omni?
That is with the stock turbo (110K miles) but with a .63 exhaust housing bolted on. That is also with BFG T/As. The turbo is huffin pretty hard to supply what the head can flow, though. After a full run, the hot side intercooler pipe is almost too hot to touch!

TBI header in an Lbody is possible, but probably not worth it.

Clay
02-11-2007, 03:44 PM
run it till it breaks....... THEN upgrade! ;)

turbovanmanČ
02-11-2007, 03:44 PM
How in the world did you ever fit a TBI header in your omni?

Will Martin has one on his and still has his power steering, :nod:

BadAssPerformance
02-11-2007, 06:48 PM
TBI header in an Lbody is possible, but probably not worth it.

I'd argue that it is worth it if other things have been updraded first, however have not seen any back to back dyono or track data.

BadAssPerformance
02-11-2007, 06:48 PM
run it till it breaks....... THEN upgrade! ;)

As the saying goes, "if it ain't broke, don't fix it" :thumb:

mo' parts
02-11-2007, 07:39 PM
Should be able to do it with an Omni for sure.

Stock Garret, '87 T1 short block, and mostly stock everything else got my full weight Shadow in the 12's

http://www.turbo-mopar.com/forums/showthread.php?t=7538

thanks JT, good read.

mo' parts
02-11-2007, 07:59 PM
my omni is full weight, full interior, just minus the a/c stuff. was running it with 15-16lbs at shift point, when i broke #4 racing a 5.0 gt stang. which i beat:) and was my first real race with the "go-cart". thats when i tore it down, replaced the piston and was staring at the welder and tbi header(free), with snow on the ground. i had all the spare parts to put something together cheap, TM style. LOL

i think the tbi header will be a great improvement for the time and $ i have in it. i have been anxious to get the car back together, but have been limited by $, needing a few parts to finish the swingvalve/exaust items(keeping the power steering, btw, no fire wall mods ). i have been thinking of putting it back with just the ported stocker and getting some times, then switching to my swingvalve and tbi header for some #'s for reference. in which i will be running a stock freshened up 88 t2 motor for the season. i plan on upgrading the turbo later and i think with the tbi header its possible without pulling the head, so i should be pushing its(pre-common block) limits by the end of the season, hopefully:) i have a few spare motors lying around...
thoughts?

BadAssPerformance
02-11-2007, 09:55 PM
FWIW, From a conversation with Miek DeMoss at FM , he said they always recommend a bigger turbo like their E2 turbo before their TBI header.