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Lets Talk Exhausts


abarth_1200

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Hi guys, so I currently have a Hyper SS with .21 3 port rtr engine and a Jammin JP-3 exhaust. Been running great, I think, its my first nitro, it seems good at mid and top end but initial throttle is a little low. Could be my tune which im still working on but how do I know which exhausts fit my engine best and improve in what area?

 

I have just bought a JP-4 pipe and also have another Hyper 7 with Macstar .28 engine in it on its way to me.

 

Which pipe is better suited to which engine and how can I find that out, any tests, figures, user reviews I cant find?

 

Is my understanding that the Jammin range of pipes are more suited to smaller engine and wont work with the .28?

 

Is the JP-3 better at low end power than the JP4 so should I keep that on the smaller engine?

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http://www.jamminproducts.com/exhaust.html

 

3 and 4 are very similar judging by the descriptions. In the past I've paired a 1 with a 21 engine to improve low power/torque and a 2 with a 28 engine for the benefits at top end. Did have a 3 for a while, way better than the standard ally pipe that came with the car.

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So I would want an exhaust that says it improves low end performance on an engine with poor low end performance to increase it. Would that then hinder top end?

Everything depends on so many things...so the question is hard to answer..

Joe Bloggs may run the same car as John Smith....same engine same fuel...gearing..plug everything....they run their cars together but Joe is heavy on the throttle and rarely will the engine see low speed...John is gentle on the gas and will often have an engine running at low speed.....the exhaust can be an easy way to tailor the power characteristics of an engine.

..but..

That does not mean to say you can make a .12 wheelie a Savage or a .36 turn 40krpm..there are limitations to what changing the exhaust can achieve. :)

 

A well tuned engine will out perform a badly tuned engine...no matter the exhaust though. 

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I hear matched pipe sometimes. So would guess low end engines with low end pipes. To get the most out of its parameters mayb.

Actually I've always thought of it the other way. For a bigger engine which has low down power, choose a pipe designed to open up the top end. Not sure if that's right or not.

 

As Anthoop says though, don't expect double the performance or even close. It is noticeable over stock pipes but no pipe can make up for a bad tune.

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Actually I've always thought of it the other way. For a bigger engine which has low down power, choose a pipe designed to open up the top end. Not sure if that's right or not.

This is what I was wondering about, why try and get an exhaust to help improve an engines weak area, why not get an exhaust to improve what it's good at.

So back to square one, almost.

How about modifying a stock exhaust, is there anything I can do internally to improve them, how about anything to change the noise it puts out, low end rumble, high end screamer etc.

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no pipe will help that ss with low down power due to the shoddy standard clutch. I would change that as it engages to low in the rev range where there is minimal usable power. Look to put some stronger springs in the clutch so it engages later. I run losi 4shoe clutches in my hypers with 2 ally and 2 composite's.

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This is what I was wondering about, why try and get an exhaust to help improve an engines weak area, why not get an exhaust to improve what it's good at.

So back to square one, almost.

How about modifying a stock exhaust, is there anything I can do internally to improve them, how about anything to change the noise it puts out, low end rumble, high end screamer etc.

...remember Joe+John...if either has an engine/fuel/plug/gearing/etc.. (from here on referenced a "set up")...that is more specialised in one area then it is better to make the most of it.....that .12 will never wheelie a Savage...no matter the exhaust...if I have an engine capable of high torque then I can make the most of that...I can tailor things to a certain extent...but it will always be an engine tailored for torque..

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Yeah I see what you mean, just not really sure what my engine is specialised in, I'm going with mid to high speed so will put the JP4 on the .21 and try out the JP3 on the .28 I can only try it and see.

I have ordered a new stock clutch bell for now, the shoes and springs stuff is a little confusing, just tell me what I need to get to do wheelies!

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You will need me to think more than needed on a Sunday evening for a Hyper to do wheelies.... :)

I do not imagine there is that much difference between a JP3/4...performance wise....both are probably not perfect for the job.

..I can say the JP2 will work better on the .28 than the JP3...

Edited by Anthoop
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I run a JP3 on the .21 much rather than a JP2...I do not have a JP4 but can only guess it is a noise restriction pipe...I do not have a JP1 and the JP2 works better on the .28 than the JP3...

In all honesty most pipes will be a little "willy-nilly" because they arr much shorter than they should be.

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no pipe will help that ss with low down power due to the shoddy standard clutch. I would change that as it engages to low in the rev range where there is minimal usable power. Look to put some stronger springs in the clutch so it engages later. I run losi 4shoe clutches in my hypers with 2 ally and 2 composite's.

one of these do the trick? how about a 14T clutch bell, thats one down from stock?

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 how about a 14T clutch bell, thats one down from stock?

Well, I learnt something there...I never knew the SS had a 15T pinion...which led me to find that it has a 48T spur.

Standard on the Hyper7 are 13/46, so then I notice that the SS uses the front/rear crownwheel+pinion from the ST (11/43) whilst the Hyper7 has 43/13.

 

So...

SS- (48/15) x (43/11)= 12.48

H7- (46/13) x (43/13)= 11.55

Fair bit of difference there if you presume the wheels are the same size and they both use the same engine(s) then I would say the SS is undergeared compared to the 7...

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  • 2 weeks later...

A bit like F1.

Lower geared for tracks like Singapore, Hungary and Monaco, higher geared for Spa, Monza, etc ...

If you're where there are longer straights and you're hitting max revs., unlike F1 you don't have a limiter other than your ear and finger, and you could damage the motor with shorter gearing.

 

Your call.

 

Al.

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