B0ZWELL

throttles should be well away from the valves for a high rpm engine. 200mm+ for a 9000 rpm engine. and a well designed port will not have the air slamming into the valve but flowing around it. a properly designed inlet port should also flow less when the valve is removed, and yes that is possible


it does make a difference although for everyday use it is a little overkill for a zero restrictive inlet. for racing where every horsepower counts the it is one of just a number of factors that can make a difference on power.

but then getting the power at the right part of the powerband can make the difference between winning and losing on the racetrack. what works on one circuit may not work as well on another where say there is more slower corners needing more torque and less top end. everything is a compromise.

Urge

Well said about everything is a compromise.

Newer ITB designs in IRL are actually casting the throttles in the ports, so the current trend is close throttles.
The AT design is thin and has no shaft holding the throttle. The claim is that it flows 99.5 percent vs no throttle or roller barrel with better control than roller.

The AT guys are all ex lotus guys with lots of racing experience. Look on their site. The had a bolt on torque improvement of 13% by reducing the throttle 4 mm, moving it closer to the port and using 2mm thin blades. This is on a highly optimized engine. It's good theory and I hope to test it. Thinking about pulling the trigger to test themes the kinslers

Urge

Hytech claimed 5+ hp pre tuning vs haywards/ jenveys which are great itbs. This is with 5 mm smaller throttles!!!!

B0ZWELL

in theory if the throttle doesn't make any difference in flow it doesn't matter where it is other than there is full atmospheric pressure nearer the cylinders ready for when the throttle is planted. also the further away from the valve the throttles are the larger they need to be because the shape of the inlet taper dictates the size. the angle into the head makes a difference as well as where the injectors are and how they spray. etc

all the reading and reasearch iv'e done always compares short/fat runners to long/thin. i haven't found any reason not to have long fat runners. compromise some bottom end to take advantage of the second pulse wave to increase hp rather than the third wave. give or take the manfold i made (16inches valve to trumpet) should have a 10% increase at 8750 for the second wave, a 7% increase at 6000rpm using the third wave and a 4% increase at 4000rpm for the forth wave. it's all theory and will be give and take here and there but it may also fall flat on it's face and just not work at all. time will tell and it'll be bolted to a standard engine with an oddball exhaust manifold.

bpaspi

I'm still convinced that a well tuned (designed) Intake Manifold with an plenum chamber makes more torque (=HP) than a ITB.
Main advantage of ITB's is Throttle response. And that the Throttles must be as close as possible placed to the head. I'm wondering if it's possible to combine both principles into one concept. Like a good airbox does for ITB's.

BTW, at 9,000rpm there is no laminar flow of the air inside the valve inlets. The turbulence is more like a hurricane inside this area.

B0ZWELL

why are you convinced that a plenum manifold will make better torque than an ITB set up? it's not a dig i'm genuinely intreaged

we look after a lot of old 50's and 60's Jaguars with all the different set ups available at the time. slide throttle with mechaincal injection, butterfly with mechanical injection and triple carbs with different length inlets and trumpets. the slide throttle injection has the injectors facing outwards towards the trumpet which on first principle is daft but what it achieves is a better fuel air mix once the air has reached the piston. the butterfly system has the injectors closer to the valve and points towards the valve.

the slide throttle engines have the edge on power.

Urge

The kinslers made no more power than larrys best hand made manifold.

However, I think my cams are not optimized for this set up and the kinslers are too big. They have only been tested favorably against twms. Even then, torque was going back and forth, the kinslers ran out longer thus had a higher top end. I've heard jenveys blow away the twms so how good are the kinslers really? Hard to tell with out direct comparisons. Hopefully we can get a good run soon on the ATs. I asked John to order, should be a few weeks.

Larry sent a note to me tonight, been working 7 days a week, bell to bell on high volume bid. Thinks he can test the Hytech cams end of month. Hopefully I get the new ITBs by then.

deepbluejh

I'm curious. At what point will you consider this project finished? I think it's pretty obvious the motor is reaching the end of it's naturally aspirated rope. From here on, I suspect there will only be tiny gains coming at large expense of money, time, and effort.

Do you plan on commercializing these efforts, or is this just a "one off". Sorry if these questions have been asked before.

Urge

You are absolutely right. I think we are at the limit or close for a streetable engine. They Hytech Cams & AT Power ITBs will be the last thing tested. Thats it.

I hope to commercialize it, but I dont have a shop and dont plan on getting one. Maybe it can be a S2KI co-op with better access to Endyn and Hytech as they are 2-3 man shops and dont cater to individuals normally.

bpaspi

With ITB's pulses are used only from that runner that is connected to it's cylinder.
An Engine with an Intake Manifold with plenum chamber can benefit also from pulses from the neighbour cylinders. So you have 2 forced intake waves.