Honda Prelude Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter #1
Is there a write up anywhere with information about swapping a b21 into a 89 lude? I have the engine in running already but I was in the middle of putting the new "91" axles in the 89 and they don't fit in the hubs. Anyone know what I need? (Or better yet, where I can find the parts)

Thanks for the help!
 

·
Premium Member
Joined
·
16,865 Posts
Is there a write up anywhere with information about swapping a b21 into a 89 lude? I have the engine in running already but I was in the middle of putting the new "91" axles in the 89 and they don't fit in the hubs. Anyone know what I need? (Or better yet, where I can find the parts)

Thanks for the help!
90-91 axles will not accept 88-89 axles, because there are more splines in the 90-91 hubs.
Just use your stock 88-89 axels they work just fine.

You can swap the B21 into the 88-90 ludes motor and tranny wise with no issues.
However, you will need to swap ecu's to run the motor properly.
But since the B21 is OBD1 you will have to get a OBD1 jumper harness or swap out the interior harness and use the B21 engine harness to run everything which means that you will need to swap the cluster as well.

And there are little things here and there that will need to be addressed.

So the choice is yours for which way to go.
 

·
Registered
Joined
·
30 Posts
Discussion Starter #4
90-91 axles will not accept 88-89 axles, because there are more splines in the 90-91 hubs.
Just use your stock 88-89 axels they work just fine.

You can swap the B21 into the 88-90 ludes motor and tranny wise with no issues.
However, you will need to swap ecu's to run the motor properly.
But since the B21 is OBD1 you will have to get a OBD1 jumper harness or swap out the interior harness and use the B21 engine harness to run everything which means that you will need to swap the cluster as well.

And there are little things here and there that will need to be addressed.

So the choice is yours for which way to go.
Can the ecu that comes with the 91 b21a1 be chipped or tuned? If not is there a different ECU that I could get that would work?
 

·
Premium Member
Joined
·
16,865 Posts
Can the ecu that comes with the 91 b21a1 be chipped or tuned? If not is there a different ECU that I could get that would work?
At this point no, there is one guy who is working on that but he is not completed.

But you can use other OBD1 ecus and get them chipped and tined, but make sure to understand what your tuning for.

PR4 OBD1, P75, P06, P28 are all chippable ECU's.
 

·
Premium Member
Joined
·
4,294,967,295 Posts
Not sure of your question. But I will throw this out just in case. If swap the wiring the b21a1 engine will work fine the b21a1 ecu.
 

·
Registered
Joined
·
30 Posts
Discussion Starter #7
I have my b21a1 swap almost finished but when I start my car it wants to Rev all the way to redline. Does anyone have an ideas as to what would cause this?
 

·
Premium Member
Joined
·
16,865 Posts
I have my b21a1 swap almost finished but when I start my car it wants to Rev all the way to redline. Does anyone have an ideas as to what would cause this?
Yes that is a huge vaccum leak, most likely your intake manifold gasket got damaged when installing it or if you did not remove the intake manifold with the swap then it had a damaged gasket to begin with.
 

·
Registered
Joined
·
30 Posts
Discussion Starter #9
Hey everyone!
I took my lude for it's first successful drive the other day! I have a few things that I still need to finish up but the swap has been coming along nicely!


Does anyone have a shifting linkage bracket for sale for a 1991 Prelude with the electronic VSS?
 

·
Registered
Joined
·
30 Posts
Discussion Starter #10
Hey everyone!
The swap has been finished and the car has been up and running for about 2 weeks now. There are still a few odds and ends that I need to finish up but the big one that I am trying to work out is this high idle that I get.

It doesn't start but seems to mostly happen after the car has some time to warm up. Then out of nowhere the car will start to idle at higher points. It doesn't surge, just stays at a high idle.
 
1 - 10 of 10 Posts
Top