Hi all,

I have recently fitted a HKS supercharger kit to my s2000 and during some road tuning i have encounter an issue with the boost.

Now the OEM map sensor struggles to measure boost beyond 10psi or so because of this i have fitted a AEM 3.5 bar sensor and everything is calibrated correctly. Now i understand the basics of superchargers and how they generate boost.

Here is a plot of my AEM EMS datalog showing engine load against RPM. As the RPMS increase you can see the boost increases but as it gets to around 7500rpm it peaks at 9.2psi and then it begins to drop down to 8. Should it continue increasing or is it simple a case of the supercharger running out of puff as the engines RPM increases?

I'm thinking it might be worth putting abit more tension on the belt incase its belt slip



Are there any tell tale signs of belt slip? i cant hear anything or see any obvious signs of marking on the belt.

 

I would rule out any other potential problems, no boost leaks? I'm not familiar with the HKS kits so I can't really chime in on all the obvious things that you might have to look out for

What clutch are you running? I don't think it's your supercharger running out of steam as you suggested, it may well be the belt slipping.

Try not to go too crazy on the tightening though, remember that if you've installed a new belt recently it takes a good 500km or so to settle in

 

Could be belt slip or a slipping clutch. Easy way to know is to tighten the belt a little then go for a datalog run.

 

Well slackened off the tensioner and then pushed it tight by hand it already went past how far it was tensioned before. Quite surprised by how much the belt has stretched. I have nipped it back up tight again but not OTT as i dont want to ruin any bearings.

Will let you know how i get on.

By the way i have the OEM clutch but if it was slipping i would expect the smell you get and also the fact that the revs rise at a steady rate on the datalogs if the clutch was slipping surely they would peak higher.

 

I'm sure the clutch is fine for now, but if it's got a few miles on it you'll probably want to swap it out eventually for an ACT + OEM combo which is used by pretty much all the supercharged guys on here

 

Yeah the plan is to change it at some point in the near future. Its done well thou its on 74,000 miles and at least 10 or so trackdays in NA form. Honda clutches have always been great quality for the price

 

Well tightened the belt up and took the car out today.

Im now making 11.5 psi boost at 8500rpm and no dips or drops as the charger spins up. That extra 2psi gives you a fair bit more power!

 

Glad you got it sorted
Snetterton this year ?

 

Some reason it didn't fill in my complete reply, that will teach me trying to do it on my ipad,

I probably wont do snetterton this year. Im not convinced the engine would stay cool on a hot trackday where your constantly in boost. Im finding that im having similar issues to Mattie where the intercooler blocks so much of the radiators airflow that it struggles to keep it cool unless you keep the fans running. I need to invest a substantial amount in either a aftercooler and bin the intercooler or just get a high performance alloy rad. Problem is they cost about £600 but cheaper than a new engine!

 

Why not try downsizing your intercooler? Pick a small one up for 50 quid from Toyosports on eBay