I've raced V8's for a long time, asphalt, 1 mile or less. We have run Honda's on 1/4 asphalt and won a lot of races. Remember guys, we can't change a lot on these engines. Basically stock. I built a GSR for a backup car. I had planned on using the stock header, it looks fine. We don't have to run a catalytic converter and we do have to run a straight shot type muffler. I'm about done with the GSR and will set the engine/transmission in pretty soon. I sat down and started looking the header over. The four exhausts come down from the head, feed into two pipes. I think that looks fine. Where the two pipes feed into one looks as though it would be restrictive. It's about two inches. I had planned on running 2 1/2 inch pipe out the side. I know a little back pressure works in drag racing sometimes but we have always wanted our exhausts to flow freer in stock car racing. We turn around 7500 twice a lap for as much as 50 laps. I have seen some really knowledgeable people on here and I just want some opinions. Am I wrong in thinking at least a 2 1/2 inch collector would be better, maybe even 3? I'm not ashamed to ask for help when it comes to Honda engines? By the way .. I specialize in building the cars, race setup and tires, not the mechanical end. Thanks in advance.

 

How much improvement are you looking for? With just bolt-ons and a tune you likely won't get much more than 170whp. It's not like a V8 where you can make big power with relatively simple mods.

 

Don't waist your time on the GSR manifold, The best OEM B series exhaust manifold design is the JDM Integra Type R exhaust manifold, has a 2-1/2'' collector as well. Even the USDM Integra Type R version is better than the GSR header. It has I believe a 2-1/4'' collector though but still a better design. Keep in mind these are still stock exhaust manifolds and will bolt right up to a B series GSR engine.

Depending on what type of racing your doing and what rpm range you will be in or using during your racing in short basically the GSR engine has great low and mid range power hence the Intake manifold design and exhaust manifold design (4-2-1). and the Type R is just in a league of its own and has a much better mid and top end than the GSR hence its Intake and exhaust manifold design (4-1). But to much comes in play on what the differences are because we are just talking about the header design. But imo the Type R is better any day all day!.

 

I will take it to a dyno when it's done. This is hard for me to explain to a lot of you guys because we have limitations by rules. I've never had a problem with squeezing all the HP I can out of an engine we run, but the headers we have used were 2 1/2 inches where the header connects to the exhaust pipe. I didn't realize a GSR header funneled down to about 2 inches. The only question I have now is is there some reason I don't know about that I should run the stock GSR header, which funnels down to 2 inches on the B18C1 or just run one with a 2 1/2 inch connection like we have on some B16A's and a few D-series engines that we use to run. I could just wait and try both on a dyno but there is a chance I might have to race the car before it goes on a dyno. I just think the 2 1/2 inch one should be better. I just wanted some opinions from people that might already have an answer. Thanks

 

wunfstgsr .. Thanks. That's what I was wondering. We have always used the 2 1/2 inch ones, but this GSR header was new to me. It really does look like a HP killer. I was just making sure there wasn't a reason that I needed to keep using it.

 

By the way. Here's what it's going in. I'm a little further along but these are the newest pictures I have.

 

 

Here's what it looked like when I started.

 

Wow man looks sweet! looks like this is gonna be a fun lil car! looking forward to the end results with this build!

Maybe this will get moved to the build and appearance thread.

 

There isn't a reason in the world to run the stock GSR header. I assume you have adequate ground clearance to run a header w/ 2.5" collector.

 

I believe he has to stay within stock mods or a stock engine..

 

I do have clearance to run 2.5 inch. I think that's what I'm going to do. Thanks for the reassurance. I'll post some pics when I get done with it. It shouldn't be more than 2-3 weeks.

 

wunfstgsr .. Actually, we can run a 2.5 inch header. They didn't limit us to any specific header size.

 

Nah, according to the OP:

 

Y'all have a really good sight here. I haven't posted much, but I have got a lot of good information from all the previous discussions. I appreciate the feedback.

 

Ok but you cant go aftermarket right? then id stay with a JDM ITR header unless you can go aftermarket cause then thats a whole other discussion.

 

Actually, the header is one of the things we don't have to run stock. I was letting you know about the basically stock part, just to let you know the engine internals were stock. I should have made myself more clear on that.

 

Even though we don't have to run OEM headers. We have never gone with expensive headers. The money we can win isn't a bunch. So far we have done just fine with less expensive headers on the B16A and D series engines we ran years ago. We had the D Series engines down so good that we were actually beating VTEC's. Reason being, no matter how much HP you have, if you can't get it to the pavement it doesn't help. Our cars HANDLE.

 

SICK!!