Don Terrill’s Speed-Talk

There is no problem in running 46 chokes. The F7 tubes are way to rich. You must get the idle jets right first to get the transition right. I use the same carb and I use F9 idle jets between 55 and 65, I have to check. How rich the emulsion tube runs during transition and part throttle is mostly dec...

What is the CSA on the Edelbrock runners? I'm assuming that's what you were talking about (the 'elbow') in the previous post. https://www.speedwaymotors.com/_next/image?url=https%3A%2F%2Fcontent.speedwaymotors.com%2FProductImages%2F3253865_L_86a1e67f-e1da-433f-b59e-e6e5146e4518.jpg&w=750&q=...

Long duration cams will do the same as shortening the runners. But, as it is said in 2 stroke tuning, pipe the port, don´t port the pipe. The runner CSA must be calculated for the engine size and max hp RPM you are planning. Then you must decide reflection and TPI will be the second reflection. Actu...

I just did a test with an Edelbrock TR1-Y manifold.
It flows 204 CFM and is as cast.
So 194 CFM for the TPI manifold is not that bad.

Erland

I put on a Edelbrock high flow elbow or whatever it is called and did a flow test.
Bare head at .500" 227 CFM. Base added 206 CFM. Elbow added 196 CFM.
I tried to flow with a tunnelram but the one I had taken had the flange welded up to high so I must take another tomorrow.

Erland

I did a flow test now with the most stock looking head that I could find. It still flowed 227 CFM bare at .500". With the ported TPI base added flow dropped to 206 CFM. Looking at the port I believe that the biggest flow loss is the floor between the head and manifold with that angle. Erland Y...

First of all, with a full length TPI will maximum power come after 5500 RPM? Some of the joy with the TPI is the incredible strength from low rpm, there are other manifolds for higher RPM. How large is the engine going to be? A 400 definitively needs larger ports than a 350. If we stay at 350 or 35...

I did a flow test now with the most stock looking head that I could find.
It still flowed 227 CFM bare at .500".
With the ported TPI base added flow dropped to 206 CFM.
Looking at the port I believe that the biggest flow loss is the floor between the head and manifold with that angle.

Erland

The longer the ports are the more friction they will give. The only way to lessen that friction is ti lessen air speed. I have to look at plenum and everything to see what can be done. I have a tig welder so building up the plenum and drilling new holes will not be a problem. But I will do some air ...

First of all, with a full length TPI will maximum power come after 5500 RPM? Some of the joy with the TPI is the incredible strength from low rpm, there are other manifolds for higher RPM. How large is the engine going to be? A 400 definitively needs larger ports than a 350. If we stay at 350 or 355...

I think that shape and area becomes before flow. It is not good to go up and down in area along aa flow path. But I will give TPI porting a try. I would use a GM hot cam as I have several, 218-228-112. And either a stock iron head or an aluminum L98 head with 1,94-1,50 valves. I have made 502 hp wit...

I don¨´t think that going up and down in area just because there is a turn is a good idea.
I have some TPI manifolds myself so I will taker a look wit a burr.

Erland

How much less hp will an engine with dual SU carbs give?

Erland

I have one test car and what is most important is that it must be fast on track. Right now I have this intake lobe: Total duration 364 Rated duration 299 Duration at 1mm 281 Duration at 0,050" 275 and lift.16.0mm My exhaust lobe is:364 300 280 274 14.5 and the lobe separation is 105 degrees. I ...

But what happens when that pressure difference is interrupted?
Doesn´t that make that intake stroke loose a lot of its filling possibilities?

Erland