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redblockpowered converts from 240 to 940

I think I read this report. I think there was something to do with the shape of the blades or something like that. If it's the same test, there was some nuances about the differences that didn't come down to just weight, but the materials used also allowed/did not allow some changes to the overall design of the impeller. Maybe one had thicker blades? Dang I can't remember.
The short version is that the TiAL turbine flows a tad less than the Inconel one. This causes higher backpressure which resulted into retarded ignition timing during the tests in order to prevent knock. That's why the torque numbers are a little lower. Now they also stated that the flow difference between the two turbine wheels is so small that it's considered "not significant".

The small difference between the turbine wheels comes from the usage of different materials, TiAL is lighter but also weaker than Inconel. Because of this the TiAL turbine wheel needs a slightly tweaked design, most importantly it needs thicker blades. This generally reduces turbine efficiency by a smidge but can be (partially) compensated for by tweaking the rest of the design.

And that's what you're seeing here i think. It's not that both turbines are already at choke flow at these 2000rpm tests, it's more like the TiAL turbine wheel is a little less efficient and needs a smidge higher pressure ratio thus reducing flow. Insignificant on itself but on the knock limited 2.0 GDI engine it seemingly makes a visible difference when using the stock ECU.
I'm not sure on Kyrk, but my impression is there's a wide variety and the option for "roll your own" if you can account for a ~30mm base circle custom grind. Kyrk basically specs profiles and they are produced by Axelsson.

When I was working with Erland Cox over the winter (hey I should update my thread) he had some opinions on AGAP cams; primarily that he changes the ramp "because his are too aggressive from constant acceleration to constant velocity". He also stated that the finish on AGAP cams is not as nice on what he gets from Kyrk. He also said for a cheap COTS part he likes the KLR T5 but that's a 12.9mm cam so a little bigger than an RSI stage 3.

You could drop Erland a line and ask for his 2c, he has been super generous with his input and time from my experience. I think we've traded like 150 emails in the past 8 months!
Erland has been awesome with advice on the General Leif project. He does use AGAP grind stuff in some of his own motors (and son’s), but did also mention that he doesn’t like their surface finish either. They’re not super polished.

I just looked at the Kyrk stuff again, it’s been a while since I did. I love how much AGAP spells out what they’re selling but Kyrk doesn’t tell you much. Their low lift numbers make the cams seem quite old school with potentially high duration to come up with the HP numbers they’re saying. Well, that and there’s the part where we think we need a bigger cam to get HP where a lot of the time it might just be a larger turbo that’s needed… hah. Their second level of turbo cam here can do 400hp it says and it’s smaller than AGAP’s smallest race profile cam. I guess turbos are a different game than NA. 😜


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Oh I picked a cam for this. Might be fun. Have to get my spring setup sorted out.

Driving around with the A cam is a step down in fun for sure. Idles like butt but haven't done any tuning. More compression is nice.

I think the TiAl setups have thicker blades. Mine has one fewer than normal to compensate. Seems to be working fine after about ~5k. Would like to get on track again before it gets cold. We'll see.