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Ram air?
Toed64 - 12/2/18 at 09:23 AM

Hello all

I have a Sylva Riot with formerly carbed R1 engine. It's fitted with GSXR 750 throttle bodies with a DTA ecu.

When I bought it, it was running very poorly, variable torque and low output and was ear-bleedingly noisy. We removed the foam air filter and fitted a GSXR air box/filter and added another silencer across the back panel.

The chap that mapped it was not keen to blow it up, so he only revved it to 11000rpm - whereas the original red line would have been 11750 (I believe). It produced 135bhp at 11000rpm: about 40bhp more than it was limping to when I bought it.

I was looking at a GSXR 750 the other day. It had a ram air system, which got me thinking. I have lots of cool air swirling around the engine from a big Subaru STi scoop on the engine cover, but no piped and sealed cold air intake. Fixing some air ducts on would be quite straightforward, but I'm not sure where to mount the intake mouths...and not sure how much difference it might make.

I'd be really grateful for your thoughts?

SPYDER - 12/2/18 at 10:46 AM

Its always worth achieving a cold air feed to the airbox but any "ram air" benefit would be tiny, if any. The ram air inlet on the bike is normally at the nose of the fairing where there should be a higher pressure area which increases with speed. The speed is key to the whole concept. Your scoop would need to be in a similarly high pressure spot or at least in an area of non turbulent air. At legal speeds it won't do squat. Above a ton, maybe a little bit. Maybe.
The ECU on the bike can make an adjustment to fueling to account for the "ram air" as it knows the speed of the bike.
Can yours?
I would concentrate on getting the cold air feed sorted and leave it at that. I'm not sure if any current superbike is using "ram air".

Toed64 - 12/2/18 at 12:37 PM

I'd been thinking about that. My car's gearing is a tad low, so it's not got great top end anyway. I'll experiment with scoops, but ideally, they'll be on the side panels to keep the screaming induction noise away from my ears!

My ecu does monitor speed and I have an air temp sensor in the air box, but no pressure sensor. Hmm...

Thanks for your thoughts.

russbost - 12/2/18 at 12:44 PM

The ZZR1400 runs ram air & claims an approx 10bhp increase with it, however what they don't tell you is that unless you're doing probably 140/150mph upwards I doubt you would ever see any benefit from it.

The other problem with trying to implement anything on a one off basis off course is how do you map for it in the ignition/fuelling? You are going to introduce more air & pressurised air, but unless that's accurately allowed for within the engine mapping you could finish up running weak & blowing the engine up if you ever did actually achieve any significant amount of pressurization

Yes, to getting nice cold air into the engine, but ram air as such is a waste of time unless serious speeds & an investment in pressure measurement & suitable mapping can also be achieved all IMHO of course!

[Edited on 14/2/18 by russbost]

cosmick - 12/2/18 at 07:19 PM

Check out my photo archive. I have made use of the air scoop on the bonnet and feed it directly into my airbox.

Toed64 - 14/2/18 at 12:17 AM

Originally posted by cosmick
Check out my photo archive. I have made use of the air scoop on the bonnet and feed it directly into my airbox.

That's a neat solution. However, I'm still tempted to use intake scoops on the sides to avoid directing the screaming intake noise toward my left ear! It's so much nicer to drive without the tinnitus afterwards...

cosmick - 14/2/18 at 07:27 AM

There is absolutely NO induction noise at all if you use an airbox. I was very concerned about drive by noise levels at track days as many people get pulled for it and mostly it is air induction noise that tips the meter over the top. Fitting an airbox cuts all the induction noise and you only hear the exhaust in my car.

Toed64 - 14/2/18 at 09:45 AM

With the foam filter and no air box, the induction scream from the Suzuki throttle bodies (only 40cm from my left ear in the rear engined Riot) was an extraordinary experience...exilarating for the first few minutes. Then I found myself feathering the throttle and trying not to snap it open to reduce the battering.

The exhaust was almost unsilenced when I bought the car. It had a straight through pipe with an empty can that looked like a small bike silencer. There was a DB Killer bolted into the tail pipe. One of the first things I did was to remove the DB Killer to see if the motor would rev out cleanly - it wouldn't! To my astonishment, it didn't seem to make any difference to the perceived noise from the driver's seat - the intake noise was so extreme that it drowned out the open exhaust.

The Suzuki air box has made an enormous difference and refitting Jeremy Philips' silencer across the back panel has brought the noise down so that I can go to Bedford Autodrome without fear of being turfed out. I just don't want to reverse the improvement by pointing the air intake at my left ear again!