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Old 12-06-2004, 08:24 PM   #1
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Default Need .21 onroad pipe suggestions

Okay, I recently bought an HPI RS4 2 on ebay. It's my new winter project car. My goal is to see exactly how fast I could get one up to for the cheapest amount. I'm shooting for 100mph, but sadly, I probably won't get there.

At the moment, I have a Wasp .28 on order. I'll try that out, and probably later on buy a nice italian onroad engine. But i'd like to try a cheaper engine to see if it's possible.

Here's my dilemna, I have no idea what to use for a header/pipe combo. I want something that will bump the powerband as high up in the RPM range as possible. What would work?

I know novarossi makes a few different 1/8 onroad pipes, but I can't tell one from the other
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Old 12-06-2004, 11:58 PM   #2
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i'd bin the idea of a wasp .28 straight away as if you're after Top speed you need an engine that REVS! as we all know high RPM = High Top speed
go straight for an Onroad .21 like a Novarossi 421P & try something like a Nova 2006 pipe & short header for top end or if you don't need a 3 chamber pipe the 9886 is still considered a good topend pipe


if you want speed you need revs not torque
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Old 12-07-2004, 12:15 AM   #3
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Well I eventually plan on going with an onroad specific .21 engine. But i'd like to see how fast you can go if you're on a budget. I'd like to avoid getting into the +$350 italian engine for now.

Anyhoo, the Wasp .28 is *supposed* to rev to 42,000rpm, but I doubt it actually revs that high in the real world. But we'll have to see. Using off the shelf parts, I can gear it to around 110mph, which will give a little breathing room for the revs.

Which would be the better pipe with the shorter header? The 9006 or 9886? Or are they pretty much of equal performance for my application?
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Old 12-07-2004, 12:41 AM   #4
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the 2006 is a 3 chamber pipe while 9886 is a 2 chamber!
ther three chamber pipes were developed as a way of making the engines quieter & "usually" things that make engines quieter slow them down slightly too!
i know the INS airbox (Intake Noise Suppressor) will cost you about 3% of your peak power!!
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Old 12-07-2004, 12:58 AM   #5
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Ah okay, well in that case, i'll go with the 9886 pipe. I don't need to worry about noise rules since the car won't even see the track.

Thanks for the help.
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Old 12-07-2004, 10:00 AM   #6
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THS Racing Pipes or the OS T Series Pipes
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Old 12-08-2004, 12:50 PM   #7
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Default INS box

INS box on properly tuned engine costs no power and can actually improve top end by stabilizing airflow at speed. Sirio 3 chamber with short spacer is an excellent top end pipe.
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Old 12-08-2004, 02:15 PM   #8
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i was quoting figures from Serpents own site, as distributors of this product i don't think they'd say it has a restricting effect on the engines if it didn't??

Quote:
Performance
Because of the optimized design, the INS-BOX unit does hardly affect the performance of the engine, it only reduces the induction noise. The performance was measured in various ways: by taking lap-times (no difference), by using data-logger technology (no difference), and on the test bench (approx. 3% difference). What can be felt is a very little loss of throttle response at low speed. But this will be the same for everybody of course. Running the car with or without the INS-BOX has no influence on the setting of the carburetor, which is proof that the air-flow is not restricted.
Using the INS-BOX has no effect on the engine temperature as it

does not restrict the airflow and the engine is not running leaner.
you can read more on the page in question HERE
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Old 12-08-2004, 04:20 PM   #9
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Would the INS Box be a benefit for me to use it? Cuz they seem rather restrictive to me.
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Old 12-08-2004, 11:27 PM   #10
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in the UK we have to use them so its the same for everybody!
apparently they make no noticable difference to lap times & trashcar says they have a stabilising effect on the airflow through the carb so it might be worth a try, might make the engine a bit more consistant to tune?

they certainly don't seem to slow the cars down at all over here
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Old 12-09-2004, 01:46 AM   #11
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I'll add that to my list for things to buy. Looks like it isn't TOO expensive at around $20.
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Old 12-09-2004, 06:22 AM   #12
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Default INS box

I know what serpents web site says,I'm speaking from real world experience.We are not required to run them yet I still run it as they have top end benefits,also while they are quiter it changes the engine tone enough to make it much easier to hear what your engine is doing,therefore easier to tune for anyone with experience.I firmly believe they are no handicap.
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Old 12-09-2004, 11:05 AM   #13
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sounds good
i only really remembered them stating that it took 3% off the peak power, but reading that information again it says there was No difference in lap times or using the datalogger!
that 3% peak was only noticed on the test bench so perhaps with the intakes pointing forwards the pressure actually builds in the INS box enough that you recover that 3% anyway
it would be nice to think that it did
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Old 12-09-2004, 01:53 PM   #14
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Holes should be perpendicular to direction of travel. Ram effect of facing direction of travel creates problems
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Old 12-09-2004, 02:02 PM   #15
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it probably leans the mixture out too much at high speed due to there being an increase in the air pressure feeding the carb, but no equal increase in the fuel delivery pressure due to there being no float bowl to equalise the pressure like say a full size car running a pressurised airbox
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