possible to recreate AJP V12?

[ps1 and swordfish]

i'm actually not chasing HP.. you're all correct, other engines more than do the job more efficiently, more reliably, and more affordably. i'm very content with 500hp and anything over 750hp is imo too scary and undriveable to enjoy properly especially without driver aids in something weighing less than an economy microcar. V12s sound and feel unique if you've ever gotten the chance to drive one. so yes, if anyone ever starts making AJP12 crate engines or manages to fit AJP6 heads on an existing block, i'd strongly support something like that (cost permitting)

[Caddyshack]

eliot said:

wiki says it was 7.7L - so 129bhp/l which feels a bit keen. Didn’t tvr bs that it broke the dyno - therefore it must of produced 1000 bhp….
for about 3 seconds…

edit: actually seems to be plenty of engines producing that and higher bhp/l - so not that fanciful. But also confirms there’s nothing special about s6 heads either.

https://www.goodwood.com/grr/road/news/2021/8/the-...

Edited by eliot on Friday 7th January 20:28

True but not many V12 engines get 100 bhp/litre. Obviously the Mac F1 did, can’t think of many others normally aspirated off the shelf, I expect the very modern Lambo s do and maybe some ferraris? I don’t think the likes of Merc, rolls, jag etc got anywhere near.

I suspect the speed 6 head is like any decently worked head that has been ported and has big valves correct for the engine and a cam to make it work…nothing more special than that. It was a hand built, race design (Ish) engine.


My speed 6 was like a bag of nails and was terrible in traffic, they junked the injection system after my early one and went with another. When my car went back to the factory for a new flywheel it came back with "piston slap" written in marker on the rocker cover.

[Olivera]

Caddyshack said:

I suspect the speed 6 head is like any decently worked head that has been ported and has big valves correct for the engine and a cam to make it work…nothing more special than that. It was a hand built, race design (Ish) engine.

I've always been confused why the 4 valve per cylinder Speed 6 engines couldn't make any more bhp/litre than the older AJP8, despite simple geometry showing that a 4 valve per cylinder head should flow much better.

I recall someone on a PH TVR forum stating they were highly comprised for the final capacities (3.6l+) as they were designed for 3 litres maximum. Hence in reality they struggled to get anywhere near 100 bhp/litre. It's telling that (Racing Green?) eventually scrapped then Speed 6 heads altogether and made the FFF head.

Edited by Olivera on Friday 7th January 23:13

[TwinKam]

Olivera said:

Caddyshack said:

I suspect the speed 6 head is like any decently worked head that has been ported and has big valves correct for the engine and a cam to make it work…nothing more special than that. It was a hand built, race design (Ish) engine.

I've always been confused why the 16 valve Speed 6 engines couldn't make any more bhp/litre than the older AJP8, despite simple geometry showing that a 16 valve head should flow much better.

I recall someone on a PH TVR forum stating they were highly comprised for the final capacities (3.6l+) as they were designed for 3 litres maximum. Hence in reality they struggled to get anywhere near 100 bhp/litre. It's telling that (Racing Green?) eventually scrapped then Speed 6 heads altogether and made the FFF head.

16 valves?

[Olivera]

TwinKam said:

16 valves?

Apologies, I of course meant the 4 valve per cylinder Speed 6 head vs 2 valve per cylinder AJP head. I've edited original post, but the points I've made still stand.

[MikeE]

All these questions and speculation about the Speed 6, Al Melling (who I'm sure you all know designed the AJP8, AJP6/Speed 6 and the initial concept for the Speed 12 is still around and has answered many of the above questions on his Facebook group, so if you're really getting the answers from the horses mouth then join the facebook group and ask him.

I believe he's said a number of times the S6 engine was designed to be a 3.6 and TVR themselves then went and increase the capacity to 4.0l. I think he also said the S6 head used lots of lessons he learned from the Jaguar Le Mans V12 engines he developed in the 80's, he's also talked recently about manufacturing some new AJP8 heads to his original design rather than the compromised design TVR developed from his design, and why the Speed 6 finger followers failed so quickly (the design was changed by TVR, there's an extremely simple fix to get the cams back to the proper design).

There's a wealth of info available if you want to ask him.