Don Terrill’s Speed-Talk

mt-engines wrote: ↑Thu Apr 25, 2024 1:50 pm Who would have thought a bigger hole would flow more?

Isn't that a misleading saying? As the port size increases for a given bore size, there is less and less space left for the valve and flow entering the chamber..



-juhana

Based on the flow curve and cross sectional areas, im not convinced the heads fit the engine well.

WAG; Maybe the air flows through the valve throat in such a way that it blocks the flow zone, reduces the available area and chokes the engine?



-juhana

I copied the test data of both heads from the video and made a comparison. Here is a port energy density comparison between ported ls3 (as i remember it) and AFR ls3 head;



-juhana

Observations from a hobbyists point of view; The flow curve shows possible intake port stability/air speed problems at higher lifts, where the port energy also drops like a tail. Heres one head im working on that i expect will help the car out of corners and also have good top speed. (igonore the ex...

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. Act...

I would say that widening the ssr is a common move, but i was wondering if that would add to the thumble?

Does anyone have experience measuring tumble with this type of floor shape? Thanks,



-juhana

Because no one wants to admit that they use more than 92% valve to throat percentage on intake.. Type 1 vw head paired with a dual port manifold work in progress.. Screenshot_2023-12-29-21-56-52-74_92460851df6f172a4592fca41cc2d2e6.jpg IMG20231229163806.jpg -juhana I have recieved something like tha...

My problem, I think it's on a more delicate area, and probably there's nothing that can be done to improve it, the ducts are pretty much stock, but the previous owner enlarged the throat area in the seat, so the seat is like straight and then 45 degrees, the seat is flush to the throat, straight, I...

Why isn’t anyone looking at runner to throat percentage Because no one wants to admit that they use more than 92% valve to throat percentage on intake.. Type 1 vw head paired with a dual port manifold work in progress.. Screenshot_2023-12-29-21-56-52-74_92460851df6f172a4592fca41cc2d2e6.jpg IMG20231...

Thanks for the answers. I picked up the heads today and they look like this;



-juhana

Why isn’t anyone looking at runner to throat percentage Because no one wants to admit that they use more than 92% valve to throat percentage on intake.. Type 1 vw head paired with a dual port manifold work in progress.. Screenshot_2023-12-29-21-56-52-74_92460851df6f172a4592fca41cc2d2e6.jpg IMG20231...

Here a lower package is in the fitting. The manifold needs work and maybe a spacer, its just been cleaned.



-juhana

I have one pair on shipping that i picked up online. The seller said they were off the -68 mustang. I see markings 302 and V2 in the picture and possible cast in recessed spring pockets? Screenshot_2023-12-28-15-30-34-02_6012fa4d4ddec268fc5c7112cbb265e7.jpg I can of course take more pictures when th...

I have sprayed more fluid when i didnt believe the results of it keeping suspended with the airflow

My shop vac has two filters, i last used it yesterday and it hasnt exploded yet.



-juhana

Im trying to think of what youre leaving out and maybe it has something to do with how the port flows with different manifolds?

Did we see the fuel vaporize before it entered the cylinder? So could we try to put more emphasis on flow instead of mixture motion?



-juhana