jackson auto machine(jam) vs cosworth
Newbie
Joined: Oct 2004
Posts: 68
Likes: 0
From: Markopoulo, Greece
I vote JAM for all my 4G63 needs.They are one of the best shops (if not the best) for the 4g63 community,their parts are top notch and of course my next ported head will be a JAM unit!And one of the most important things....you can call them or email them and they will be right there to help you!
Then I guess the biggest port wins, huh, Ted?
In the real world, port velocity is as important, and maybe more so, than ultimate flow. I bet Cosworth has hundreds of hours in R&D on this head, and thousands of hours on other heads in finding what works and what does not. You might remember the two decades of F1 domination, and the development of the 4 valve head as prior examples of their work.
The only way you'd be able to get an accurate comparison of the two in a real world environment is to put each of them on the same motor, under the same barometric and temperature conditions, and see which one works best. Even with that kind of test, one might develop more power with one turbo, while the other may improve with a turbo switch.
Until that happens, the rest is just bench racing.
Evolving Member
Joined: Sep 2004
Posts: 381
Likes: 0
From: In my house
The only way you'd be able to get an accurate comparison of the two in a real world environment is to put each of them on the same motor, under the same barometric and temperature conditions, and see which one works best. Even with that kind of test, one might develop more power with one turbo, while the other may improve with a turbo switch.
Until that happens, the rest is just bench racing.
Until that happens, the rest is just bench racing.
+1 great post, but I don't see any vendors going out of their way to do this kind of test......
No, first-hand experience in 4G63 development, racing and performance is the difference, and JAM has FAR more time in developing their 4G63 CNC port programming than Cosworth does with this head and engine, times 10. This being the case, assuming that something is even equal (much less better) just because it has "Cosworth" stamped on it is unreasonable, and amounts to pure 'bench racing'.
Tell us how you came to this conclusion, Ted? More assumptions, I bet.
How much time does JAM have specifically in their head development, and what is the source of your facts?
How much time does Cosworth have in their head development, and what is the source of your facts?
What flow equipment and modeling programs did each of them use?
How much did their past experience with pure racing car engine development play a part in fine tuning their approach?
How about port velocity? What do you know of the comparison between these two heads on that important issue?
Moreover, what makes you think that "more time" equals better outcome? I could spend a thousand hours on something, and you could spend ten minutes, and your outcome might be better. Heck, if time is the only factor, then Buschur is king, and the others can go home.
I'm not knocking JAM. I'm simply observing that your post is, at this point, only your opinion, and you continue to make unsupported statements, like the one above.
Last edited by CO_VR4; Jul 11, 2007 at 07:13 AM.
Short blocks are a different discussion than ported heads. 
If you want to discuss short blocks, there are a number of high quality alternatives sources, including AMS, Buschur, and Magnus Motorsports, and JAM. That comparison is wide open, and depends on your personal preference on components they use and price.
If you want to discuss short blocks, there are a number of high quality alternatives sources, including AMS, Buschur, and Magnus Motorsports, and JAM. That comparison is wide open, and depends on your personal preference on components they use and price.
Secondly, I've seen direct, back-to-back flow data from two heads that outflow the Cosworth head by a comfortable margin, those being from JAM and ISP. This is not an opinion.
Given these supporting facts, I base my conclusion that stamping "Cosworth" on something guaranteees nothing aside from the fact that it's put together by Cosworth. Any claim that the Cosworth head is 'better' by sheer virtue of its name is baseless. Anyone is welcome to twist this any way they see fit, but that is the logic and basis for my educated opinion, plain and simple.
Last edited by Ted B; Jul 11, 2007 at 08:24 AM.
