Monoblock Pipes?

"Dear Ralph" December 27, 1997 0
Dear Ralph, I am looking into purchasing a set of performance pipes for a ’96 Indy XCR 600 (XLT engine), and I am wondering...

Dear Ralph,
I am looking into purchasing a set of performance pipes for a ’96 Indy XCR 600 (XLT engine), and I am wondering the main difference between the different types of pipes available. For example, I understand there are both Stockblaster and Modblaster pipes from PSI. What is so different between these? I will be porting my engine and I am looking for the pipes (and any other mods) that will give me more power towards the top end.

Ryan Valin

The difference between the “Stockblaster” and “Modblaster” pipes from PSI is that the Stockblaster pipes are designed to work with a stock engine, one that has not been ported. Each set of pipes is RPM sensitive, and the RPM that a stock engine configuration is going to breath the best and make the most power is very different from the RPM that a ported engine will spin best at. The Modblaster pipes therefore are dimensioned for a higher operating RPM that a ported engine is going to breath better at. In both instances, the pipes are designed to make the most power for the operating RPM of the engine configuration. In the case of these exact pipes from PSI, there is no real difference between the silencing systems used on the pipes. However, on pipes from many aftermarket manufacturers (including PSI) for the newer engines you now are being offered more choices of silencers. Take a look at the “Silencer Science” article in this issue of SnowTech to gain a better understanding of how silencing the exhaust effects power output levels and you may be surprised.

You didn’t mention what you would be using your sled for, but you did mention that you plan on porting the engine. This XLT engine is very solid and reliable when limited to basic bolt-on mods, but porting and big bores tend to greatly reduce the reliability of this particular motor. I do recomend changing the heads, they help quite a bit. As far as changing the airbox or installing cone type filters, I do not suggest it for trail riders with this engine. The increased airflow really makes dialing in the jetting difficult and slight temperature changes really upset the balance here. Beyond pipes, heads, clutching, and gearing there is not much else that I would recomend for trail riding.

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