Exhaust Design

[Solcambs]

Has anyone done any research into later oil cooled motors e.g. GSXR1100M/N. Especially exhaust header diameters and results on the dyno. I'm particularly interested in anyone who has played with exhausts on a 1216 with higher compression. Enquiring minds and all!

[Fula28]

I've run high comp, with micron 4-2-1 40mm  I.d headers, Then micron gsxr  1000 serpent headers made nearly 8bhp more and 12lbs torque. Then ran 4-1 titanium 38mm I.d system lost 5bhp. 

Akro 40mm I.d systems I'd love to try one for comparisons, 

[Gammaboy]

Back in the old old days of OSS, there was a bunch of dyno comparisons that Mr7/11 did with different exhaust systems on his beast... I imagine that is all lost to the winds of time.

[KATANAMANGLER]

8 hours ago, Gammaboy said:

Back in the old old days of OSS, there was a bunch of dyno comparisons that Mr7/11 did with different exhaust systems on his beast... I imagine that is all lost to the winds of time.

Oh ye of little faith. Is this it?

[gsx]

Well cool 

[CockneyRick]

On 1/25/2018 at 6:46 AM, KATANAMANGLER said:

Oh ye of little faith. Is this it?

GoldenBollocks strikes again!  

[Sheep]

On 1/24/2018 at 10:01 PM, Fula28 said:

 Then micron gsxr  1000 serpent headers made nearly 8bhp more and 12lbs torque.

Are these the ones that had a 'squashed' profile on the downpipes...ie like a cobra (hence the serpent name).....I always wondered if they actually worked or not!

[Fula28]

Yes there the ones chief, we only got it by chance £780 full system , blagged for £165 on that site . Worked a treat and 0.5mm stainless light and well made too.

[Solcambs]

Thanks for the info everyone ... I'll shall read and consider what to do with my Kat ... off to read the old site thread. Cheers @KATANAMANGLER

 

[KATANAMANGLER]

Go to the PP and 7/11 sections they are intact. Most of the threads are not complete. The wayback snapshot doesn't run that deep.

[Dezza]

Is there a general difference in the effects of having 4-2-1 headers compared with 4-1 headers? In other words, what is the advantage of having 4-2-1 given that this configuration is clearly more costly in time and materials to fabricate? I ask as I have a system for an oil cooled motor that has 4-2-1 headers, and these make the system really long and aesthetically unappealing, i.e. ugly.

[Solcambs]

4 minutes ago, Dezza said:

Is there a general difference in the effects of having 4-2-1 headers compared with 4-1 headers? In other words, what is the advantage of having 4-2-1 given that this configuration is clearly more costly in time and materials to fabricate? I ask as I have a system for an oil cooled motor that has 4-2-1 headers, and these make the system really long and aesthetically unappealing, i.e. ugly.

In normal application, all things being equal, a 4-2-1 system would give more mid-range than a 4-1 IIRC. I'm with you on the looks front though!

 

[clivegto]

The yoshimura system & the cobra system I have look like 4 into 1 systems but they have a split in the colletor box making theme 4,2,1. Pic is cobra one.

[dupersunc]

4-2-1 will have more mid range as has been said. The down side is a slight loss of top end power.

The length of the secondries is a really powerful factor. The spliner in the collector shown above won't do a lot.

General rule the longer the secondries the lower down the rpm it will help torque.  6-14" are typical lengths.

I've seen 20bhp gains over 2500rpm in the mod range vs 4bhp loss at peak on 4cyl car race engines. Between 4-2-1 and 4-1.

Given a choice I'd go 4-2-1 every time.

[Dezza]

59 minutes ago, clivegto said:

The yoshimura system & the cobra system I have look like 4 into 1 systems but they have a split in the colletor box making theme 4,2,1. Pic is cobra one.

That is interesting. The one I have is also Cobra but is 4-2-1. I understand the benefits but it makes the system really long, with the positioning of the end of the silencer can up at the back of the bike well past the rear wheel spindle

[Solcambs]

On 24/01/2018 at 10:01 PM, Fula28 said:

I've run high comp, with micron 4-2-1 40mm  I.d headers,

The Harris exhaust that I'm using is messed with ... but, it is a 40mm ID header based 4-1. I do plan to try and mess about with a set of bandit 1200 headers. Realistically I am floundering around a bunch available options.

• Racefit Legend based custom exhaust - possibly too loud, very expensive, looks great, and friggin light. Unknown effect on power and torque .
• Bandit headers mated to the Harris end - may involve a sump swop, and unknown effect on power and torque
• Akro GSXR1100 full exhaust - possible fit, but unknown fitment with the GSX750 frame ... looking for tight close fitment to bottom frame rail. Noise output should be good, likely good all round performance. Reasonable cost. Looks slightly naff on a Katana based bike IMHO ... but functional.
• GSXR modern serpentine headers mated to oldskool rear, custom mid pipe. reasonable cost, looks probably OK, though the headers would not follow the frame rails. probably a reasonable power output.

[Dezza]

1 hour ago, Solcambs said:

The Harris exhaust that I'm using is messed with ... but, it is a 40mm ID header based 4-1. I do plan to try and mess about with a set of bandit 1200 headers. Realistically I am floundering around a bunch available options.

• Racefit Legend based custom exhaust - possibly too loud, very expensive, looks great, and friggin light. Unknown effect on power and torque .
• Bandit headers mated to the Harris end - may involve a sump swop, and unknown effect on power and torque
• Akro GSXR1100 full exhaust - possible fit, but unknown fitment with the GSX750 frame ... looking for tight close fitment to bottom frame rail. Noise output should be good, likely good all round performance. Reasonable cost. Looks slightly naff on a Katana based bike IMHO ... but functional.
• GSXR modern serpentine headers mated to oldskool rear, custom mid pipe. reasonable cost, looks probably OK, though the headers would not follow the frame rails. probably a reasonable power output.

Which pipe options have you got already/have acccess to? Maybe borrow some different options and see how they compare. Would be interesting for anyone to do if dyno access was available. If so, I have a Cobra 4-2-1 system available