H23 vs H22 exhaust - revisited. - Honda Prelude Forum

yohan420 · 08-26-2004, 11:09 AM

Ok, A long tim ago I was asking questions about the H22 vs. H23 exhaust ..

I'm doing my engine swap so I'm finally able to compare these.

I have an H22 / H23 downpipe I'll be photographing.

I can compare each and every flange on the exhaust and will take pictures of this too.

Facts:
An H22 cat-back exhaust will fit on an H23 exhaust, but the flange on the cat needs the holes modified so that they are either farther out from the pipe, or closer in, otherwise direct bolt on.

H22 is longer, so an H22 exhaust sits farther forward on an H23 engine. This is causing my muffler (Greddy SP) to rattle on the rear control arm (could be 4ws specific).

On the header, the H22 and H23 ports do not match up.

I have heard the h22 exhaust is 1" - 1 1/2" inches longer than H23.

My hypotheisis:
Because the downpipes are side by side and dont appear to have much, if any difference in length (h22 is maybe half inch longer?) I think that the rest of the length resides in the Exhaust Cat. I dont know at the moment if the flanges are different.

I'll photograph this and call an exhaust shop, i've been told they have books with the length/fitment of all cars and what parts are how long. I'll find this out for sure.

MidNKight-lude · 08-26-2004, 12:45 PM

^^ say what? are you saying that a h22 exhaust is longer then a h23?

cause my greddy EVo on my Si, fit perfectly and i dont have a single problem with it.

yohan420 · 08-26-2004, 05:22 PM

There was a thread on h-t quit some time ago that showed a vtec exhaust on an si prelude, and the same exhaust on an vtec prelude (both 4gen) the exhaust stuck out about an inch longer on the H22 ..

I think its in the downpipe, shadowz just said the Cat is the same length.

MidNKight-lude · 08-26-2004, 05:40 PM

eh, i have no clue. but my exhaust fits perfectly... i dont' really see a different. i have look against other vtec lude with similar exhaust, and the look the same. o wellll.

vtecprelude · 08-27-2004, 09:03 PM

I ordered Toucan header for my Si and compared it to a DC VTEC header I still have (for SALE). The lower pipes are indentical in every way.

munscher · 08-28-2004, 12:33 AM

h22 exhaust is longer than h23 exhaust.... ihad to cut out about a 1.5 inch sectino of my old school RS*R exhaust to fit my h23. the mounting holes also had to be slotted outwards (away from center) in order to fit my h23, which means the holes on an h22 flange are closer to the center. hope this helps.

yohan420 · 08-30-2004, 10:43 AM

When I took pictures of the downpipe when I have it sitting upright side by side,the length looks the same.

When I have themlaying down side by side, the H22 looks longer by 1/4" - 1/2" ...

The CAT would be a different p/n because of the flange so hondaautomotiveparts can't even provide asistance.. dammit ..

I'll just end up taking my car to an exhaust shop in town and tell them to fit my high flow cat w/ flanges and make sure the back end doesnt rattle.

open downpipe baby.. OOOH YEA!

UWNTSUM · 08-30-2004, 09:14 PM

Hmm, i just put a apex ehaust off a auto si onto my 93 vtec with no modifications what-so-ever. Wasn't too short or too long.. fit perfectly

yohan420 · 08-31-2004, 11:01 AM

it still fits, just that the exhaust tip will either stick out a bit more ...

blahblahblah · 09-01-2004, 10:15 PM

So do you have to modify a vtec exhaust to fit on a SI or will it directly bolt on...thats all i want to know

munscher · 09-01-2004, 10:25 PM

i cut about an inch and a half out ofmy midpipe to make my vtec RS*R fit my Si

ExodusFX · 09-02-2004, 08:28 PM

I've got an old school vtec RS*R on my Si and we had to do absolutely no modifications to put it on my car. Straight bolt on affair.

yohan420 · 09-07-2004, 01:49 PM

ok, the H23 is on top (with cat attached) H22 is on bottom..

the angle may be deceptive but I made it so the flange on the flex pipe is at the same spot .. in the 2nd picture it looks like the h22 is longer but when they are both with the header flange facing up they look the same ?? ..

genlude · 09-07-2004, 03:02 PM

From the pictures, the only difference I can see is the flex pipe on the H22 is longer than that of the H23. I wonder if it makes a difference

Nexis · 09-07-2004, 09:49 PM

I am in the middle of doing my swap and other than the difference in piping size, I don't see any overall difference...If you go to pretty much any aftermarket company, skunk2, apexi, greddy, ect they make an exhaust for the 92-95 prelude with no difference between the Vtec, the Si, and the S. I agree with what was said earlier, when X01VTEC got his 92 4WS we took his apexi N1 off of the wrecked car and put it on the new one, the wrecked one being a VTEC, and saw no difference and had no problems with the way that it hangs.

4thGenReady2Go · 09-07-2004, 09:57 PM

Everyone has a different story it seems ... my RS*R (newer version, ceramic coated) fit with absolutely no flange modification, it bolted right up. The only modification necessary was the long hanger (i think the second to last one) had to be pryed down a little because of control arm clearance, but the muffler sits fine, and it doesn't look like it sticks out at all.

yohan420 · 09-09-2004, 01:39 AM

hmm ... can you explain what you did exactly with the hanger arm to clear the control arm .. and this is 4ws ??? ..

I should do it to mine .. It's going to the exhaust shop probably this weekend to put on the high flow cat I got .. started my H22 today .... ooo I feel good.. 1month down and finally she's nearly drivable.. wheels, hood, and bleed coolant system

4thGenReady2Go · 09-09-2004, 10:17 AM

Quote:

Originally Posted by yohan420

hmm ... can you explain what you did exactly with the hanger arm to clear the control arm .. and this is 4ws ??? ..

I should do it to mine .. It's going to the exhaust shop probably this weekend to put on the high flow cat I got .. started my H22 today .... ooo I feel good.. 1month down and finally she's nearly drivable.. wheels, hood, and bleed coolant system

ok, mind you I did hardly any of the work, but I was around when all of it was done, so I at least saw what had to be done to the hanger. I don't have 4ws, sorry (you are because you need comparison, and I am because I don't have it

) but it's the hanger which probably sits "highest" up on the bottom of the car, in front of the pass. rear wheel, and probably the hanger closest to the side of the car. Anyway, I actually could pull the rubber high enough to hook it on the hanger, so the tech grabbed a breaker bar and pried/bent the hanger so it's hook hung lower. After putting it on, I realized it was a good thing too, because the rear pas. lower control arm (but only when full extended down, as if when the car is airborn [ie, on a jack] and the wheel has distanced itself as much as possible from the top of the wheel well) almost was in contact with it before when I was trying to pull the rubber up and hang it. Other than that, it went in fine. Take a peek at your rear suspension and see if it'll be easier/harder, and let us know.

95PreludeSi · 12-15-2004, 06:50 AM

Quote:

Originally Posted by yohan420

ok, the H23 is on top (with cat attached) H22 is on bottom..

the angle may be deceptive but I made it so the flange on the flex pipe is at the same spot .. in the 2nd picture it looks like the h22 is longer but when they are both with the header flange facing up they look the same ?? ..

So to me, except for the flex pipe these two look almost identical. I just received my JDM motor last night and it didn't come with the down pipe. I'm swapping a H22A into a Si (w/H23A1). Does anyone know if I can use my H23 down pipe and bolt it up to the H22A exhaust Manifold?

Absolut · 12-15-2004, 11:19 AM

Ok Ok....

I Had a 93 4WS, I did a JDM VTEC swap. During the swap, I installed an RS*R catback, the OG catback.
I bought my RS*R for a VTEC car, Ryan, bought his RS*R at the same time for his Si.

The VTEC version would not bolt up to the Si cat, bolt pattern problem. The OEM VTEC cat is bigger and longer than the Si version.
I ending up using the OEM VTEC header and downpipe from the JDM motor, a Carsound Cat made for a VTEC motor and my RS*R VTEC cat back. No clearance problems with the 4WS, it even stuck out under the bumper the same distance as the Si version.

IIRC I had the use a shorter rubber thing the exhaust hanger in the rear to get the pipe to lay correctly, I think the hanger lenght differance is 4WS specific.

Bottom line. If you convert you whole exhaust system (Header-downpipe-cat-midpipe-muffler) to VTEC, it will work. It's the half Si half VTEC systems that have issues.

I was missing the B pipe, (what you have in those pics ^^) when I got my motor, I bought one for $40 from a gone PO member.
I have the OEM JDM A pipe, (the part that bolts to the head) you can have for free if you pay shipping. It has a broken stud in it still, but with a little elbow grease it can be removed. I can piost pics if your intrested.