I'm seeking some information from anyone who has ever tried to use a Hytech Replica Big Tube on a regular b18c5 with intake and exhuast. Would too large of a header reduce overall performance of any engine? And if so why? I did 2 mods to my car recently (Installed Big tube header and replaced my 4th gear to a slighter shorter one) but i'm leaning towards the header being the perpratrator. I have not been on a dyno but my car used to trap 160km+ now it sometimes traps 155 and less on street tires it also feels sluggish higher up in the Rpm range. Thanks for any advice.

 

I think its the 4th gear mod . The hytech big tubes have been PROVEN to make power on 1.8lt-2.1lt engines time and time again.

 

im almost positive its not the header also

 

well i read on these headers on another site that were selling them and they say the big tube is recommended for 1.8-2.0 or 2.1. Fine, but they also mentioned High Output 1.8 including Large Cams as well as High Compression. I don't think i fit into that bracket.

Also in this performance thread. I would believe the substantial gains advertised with these dyno graphs on a 1.8 would be the recommended small tube.

https://honda-tech.com/forums/performance-45/famous-replica-header-%2Arace-proven-design%2A-low-prices-nitrate-coated-2052395/

I guess there is only one true way to find out. and that is to try a different header first. Which is easier than going into the gearbox. Still curious if there is anyone there that has tried the big tube on a stock 1.8 b18c5?

 

I was running the JDM DC 4-1 Header, I switched to the hytech big tube header on my b18c5 with just a SRI w/ velocity stack and stock internals. I had it welded to a 2.5" exhaust system, the difference to me was like night and day. I haven't put it on the dyno yet but i can tell mostly in the low-mid torque range

 

i tried both the big tube and small tube versions on a 230hp b20vtec that i had. big tube made 5 less hp across the board

 

Well i haven't been on a dyno as yet either.. and i can feel and increase in torque in the low to mid-range rpms. But it just feels pretty weak up top.

 

How on earth can a shorter 4th gear reduce trap speed if you're not going into 5th before finish? My trap went up from 163kmh to 167kmh just by a shorter 4th and a little weight lost.

 

the header is too big. the big tube is designed for 2L motors

 

I share the same sentiments. I am going to put back on the JDM 4-1 and tell you guys the outcome as soon as i get the chance.

 

The big tube is designed for high output 1.8lt engine and 2.0lt engines. His car has a full 2.5" exhaust, CAI, Skunk2 Pro series manifold, 68mm TB, compression in excess of 12.5:1. If that isn't classified as high output then my 240hp setup is mild also.

 

That trap speed he is refering too was not recorded on a timeslip...it was recorded obviously by him looking down at his speedo when he thinks he crosses the line.

 

Anyone got any dyno comparisons with just this mod (big vs small tube)??

 

u can read all the **** that is posted online and believe it. i on the other hand have tried a few different combo's myself and know for a fact that the big tube is designed for 2L motors. these manufacturers know that the majority of people run 1.8's so they offer up a free tray of fecal matter to the idiots that buy into it. this is exactly why i rarely post or try to summize things in as few words as possible. bigger is not better, but many people choose to believe so. and wtf makes his motor a high output build?! his s2 im, cai, or is it the 68mm tb?? oh wait, i got it.....its his oem cams, rods and pct's @ 13/1 c.r. tuned via vafc. lol. the op's motor is in no way a high output 1.8 nor does it need a header that is too dam big.

 

I totally agree man. Thanks for clearing the air.

 

i've had the big tube on a stock GSR with intake/exhaust/flywheel,UNTUNED, i was a car and a half faster and after like 7k it lag'd a little and the ground clearance sucks.

 

Bump: From what I've researched the big tube on a 1.8 work is you do tuning beyond streetable(stage 2). Definitely for 2.0 liters. No one says it, but it sounds as if your b would make about 215+whp, a big tube is a good idea.

 

the headers are over kill ... you can add things to make it flow better but if you don't add things to help you beather better then your flow is just wack... kinda like trying to add a big fireman water hose onto your normal house hold water outlet ... yea the hose is bigger but is it gonna flow more then b4?

 

stage 2? your play video games too much

 

Makes a lot of sense.... and a shorter 4th gear should definitely increase trap speed ...the header has to be the problem

 

very simple way of putting it

 

It doesn't have to do with flow, it's exhaust velocity and scavenging. Read up on it and do some research on the tri-y (4-2-1) headers and 4-1 style headers. To make it short, the smaller tubes actually work better at for sucking the exhaust out other than letting it dump out. This leads to higher volumetric efficiency and thus, power.

 

like an old or still around race team right? s.v.p

 

I have a Big Tube replica and the ground clearance blows...i can look at the ****er and tell its too big. I bought it in hopes of going with a more radical build but that didn't pan out. I'm willing to trade for a small tube and ill pay to ship it. It's certainly better than the 4-2-1 megan racing 2.25" header i had before though. i fear im not getting enough wake and suffer reversion up the intake side due to underscavenging and incorrect cam timing..i know i can dial most of that out but the small tubes would be ideal. *sigh*

B18c1
USDM Type R Pistons
remaining bottom end stock
supertech high compression valves
milled head
00-01 type r bumpsticks
type r intake springs
gsr intake springs on exhaust side
2.5 inch piping
AEM v1 CAI modified to Short Ram
Skunk2 ITM
Edelbrock 65mm TB
more **** i didnt name probably
stock injectors
soon to get Neptune Demon board
compression at about 11.3ish to 1