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B21A +T ... Max output

R

reini

New member
Joined
Aug 20, 2015
Location
Austria
Hi,

I read a lot of tune my b21a. (244, '76)
But there are few questions.

- What boost / hp can the stock b21a handle? (Pistons, rod, ...)
- What about the transmission?

I want to get out about 300hp. Is this a problem?

I hope you can help me.

Best regards
Reini

(Sorry for my bad english :oops:)
 
Assuming your transmission is an m46, it's weak. I think I've read that the b21 internals would be find at 300bhp. Not sure if k jet will be too easy to get there though..
 
Thanks, that sounds good.

I had zenit/stromberg carburetor :cool:

No idea what to buy to change the carburetor. Megasquirt, UMC,.....:oogle:
 
What kind of transmission?

Engine is pretty stout as is, one issue will be the compression ratio. It's a bit harder to blow a lot of boost into a high compression engine.
 
Ah, that's pretty damn low for a normally aspirated engine.

Is it a manual trans or an automatic.

Manual trans is either an M45 or an M46 at that age - either way it's not going to make it all the way to 300 hp. It will likely break somewhere between 225 - 250 hp. Probably 3rd gear.

The stock clutch will slip before that happens though.
 
T5 swap is popular here, but that's because there are lots of Mustangs and Camaros in the junkyard to supply those transmissions.

Over there in Austria - I'd be looking into an M90 swap?
 
Although, really, worry about making enough power to break it first, and replacing it second.
 
Well considering your car is from 1976. It has a B21A engine with very weak conrods and carbs?. A weak M45 gearbox and a tiny 215 mm clutch. You need to upgrade all of those to get even close to 300 hp.

Your clutch is good for maybe 200 hp.
Your gearbox will break between 200-225 hp.
You conrods will bent somewhere between 200 and 250 hp (calculated guess)
You can install 1983-1984 M-rods in your engine, but then you still need to upgrade the flywheel, clutch, gearbox, fuel management, etc.).

The easiest way to reach 300 hp would be:
'90+ B230FB motor with block mounted distributor (volvo 240)
'90+ turbo manifold + big turbo (T3/T4 .50 trim?), 3" downpipe, 3" intercooler hoses, big ebay intercooler.
M90 gearbox from volvo 940 + retroturbo.com conversion kit.
M46 dogdish flywheel
Volvo 940 diesel clutch.
Microsquirt ECU.
 
mark244turbo said:
Well considering your car is from 1976. It has a B21A engine with very weak conrods and carbs?. A weak M45 gearbox and a tiny 215 mm clutch. You need to upgrade all of those to get even close to 300 hp.

Your clutch is good for maybe 200 hp.
Your gearbox will break between 200-225 hp.
You conrods will bent somewhere between 200 and 250 hp (calculated guess)
You can install 1983-1984 M-rods in your engine, but then you still need to upgrade the flywheel, clutch, gearbox, fuel management, etc.).

The easiest way to reach 300 hp would be:
'90+ B230FB motor with block mounted distributor (volvo 240)
'90+ turbo manifold + big turbo (T3/T4 .50 trim?), 3" downpipe, 3" intercooler hoses, big ebay intercooler.
M90 gearbox from volvo 940 + retroturbo.com conversion kit.
M46 dogdish flywheel
Volvo 940 diesel clutch.
Microsquirt ECU.
Click to expand...

The rods are arguable. My '77 block has been dealing with around 260-270 crank hp and a blown head gasket with plenty of detonation for over a year. All Pistons were at exactly the same deck height ( 0.015" under). So they either all bent the same amount or the rods are stronger than they get credit for. Either way, runs pretty smoothly.
 
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