Discussion
Dunky Boy said:
Why on this forum is the V8 referred to as AJP but the Speed Six not. Are they not both AJP engines. My understanding was the V8 is an AJP 8 and the Speed Six an AJP 6 or am I incorrect.
Both engines were primarily designed by Al Melling.The V8 was the first engine and as correctly stated above the letters are the first initials of the three men involved.
The Speed 6 design is based on the AJP 6 but it has a number of differences.
For a number of reasons, one being a break down in the business relationship between Peter Wheeler and Al Melling, the Speed 6 was redesigned by TVR enough to be designated a new name hence Speed 6.
There was an article published in the October 2011 edition of Sprint that outlined the differences and similarities.
Dutch_Cerbera said:
i thought that the Speed 12 is based on the AJP 8 and the Speed 6 is kind of half a Speed 12. So i thought because if that Speed 6
The AJP 8 doesn't share any components with the Speed 6 as far as I'm aware. The Speed 12 engine only used the cylinder heads of the Speed 6. The crankcase was hand fabricated, so all three are significantly different.V8 GRF said:
The Speed 6 design is based on the AJP 6 but it has a number of differences.
And why so many went...Pop...
I had the pleasure being behind a Tuscan when it accelerated away, to see water coming out the exhausts...
Most out there have been fixed I believe of the "differences"
V8 GRF said:
Most of the issues were attributed to the use of poor quality components rather than the actual design of the engine.
It's been done to death on the speed 6 engine forum and there is still lots of hearsay and rumour about the difference between the AJP 6 and Speed 6.Some say the AJP 6 needed changing to make it functional and that the original destroyed itself on the dyno while others claim the Speed 6 was modified to make it significantly different from the AJP6 to avoid legal issues.
I believe lots of 'fixed' engines have better quality components (and non Indian sources chocolate parts) and modifications to the head to improve oil flow. The AJP 6 certainly had more oil ways in the head, so it's highly probable that the Speed 6 suffered because of those changes.
C3BER said:
On this forum there are ex tvr employees who know all the details of everything. Which makes me wonder why we ever get rumours on why it was this way or that.
Most of them don't want to get involved and as was said above it's already been done to death.I have to say though that my piece in Sprint written in conjunction with Dave Davis who owns the AJP 6 drawings is pretty comprehensive and dispells a lot of the rumours.
PDFs of the article are here: (11MB download so might be easier to right click the link and 'Save target as......')
http://www.rndengineering.co.uk/downloads/SPEED6%2...
kss after they have given the answer. 
Wish I'd remembered that before I put this month's article in. 
.. 
.. Yes, thank you for posting that.
Wonder what different elements of highlighted possible corrections the Dom's and Jason's of the world use when they rebuild/blueprint.
Personally, I still think the Sp6 engine is a better overall engine than the AJP8, albeit the bang-engine has it's own specific character.
Wonder what different elements of highlighted possible corrections the Dom's and Jason's of the world use when they rebuild/blueprint.
Personally, I still think the Sp6 engine is a better overall engine than the AJP8, albeit the bang-engine has it's own specific character.
Beast said:
Yes, thank you for posting that.
Wonder what different elements of highlighted possible corrections the Dom's and Jason's of the world use when they rebuild/blueprint.
Personally, I still think the Sp6 engine is a better overall engine than the AJP8, albeit the bang-engine has it's own specific character.
Hopefully you'll be able to hear that from the horses mouth. However, I'm pretty sure I'd heard that Don modified the heads to improve oil circulation, then rebuilt with high quality parts. Wonder what different elements of highlighted possible corrections the Dom's and Jason's of the world use when they rebuild/blueprint.
Personally, I still think the Sp6 engine is a better overall engine than the AJP8, albeit the bang-engine has it's own specific character.
I'm pretty sure not all of the 'issues' described in the article are addressed, probably because the reliability he achieves from his engines is very good without them.
Beast said:
Yes, thank you for posting that.
Wonder what different elements of highlighted possible corrections the Dom's and Jason's of the world use when they rebuild/blueprint.
Personally, I still think the Sp6 engine is a better overall engine than the AJP8, albeit the bang-engine has it's own specific character.
I can buy that people prefer the character of the S6 to the AJP8 if they have driven both. I can't buy that the S6 is a better overall engine than the AJP8 until it achieves the kinds of mileages that the AJP8 routinely does without rebuilds. Wonder what different elements of highlighted possible corrections the Dom's and Jason's of the world use when they rebuild/blueprint.
Personally, I still think the Sp6 engine is a better overall engine than the AJP8, albeit the bang-engine has it's own specific character.
Steve_T said:
I can buy that people prefer the character of the S6 to the AJP8 if they have driven both. I can't buy that the S6 is a better overall engine than the AJP8 until it achieves the kinds of mileages that the AJP8 routinely does without rebuilds.
It depends on how you define 'better'. Even discounting reliability, they're difficult to compare since they're very different in character.
Inevitably, people will prefer one to the other based on what they want from an engine. The speed 6 is certainly easier to drive around town, and the 4.5 AJP is certainly more powerful*.
- Assuming they're stock.
This easier around town stuff... I find the V8 has better low end gruny than the Speed 6. You don't push the pedal very far to get the torque though. You can be less precise with the Speed 6 without the can reacting too much. Is that what people mean? If so, I don't find the V8 in any way difficult to use in town so I'm not completely sold on the perceived benefit of the Speed 6. I do like the Speed 6 as an engine, don't get me wrong, but it's not as though the V8 has you kangarooing up and down the High St!
I've driven both but only owned an AJP8. My V8 is easier to drive slowly and at lower revs than the S6.
I suspect most owners would agree. It will routinely rev to 7200rpm; I suspect you wouldn't want to do that too often with an S6.
To produce nearly 100bhp per litre (from a well fettled Red Rose anyway) from a naturally aspirated
2-valve per cylinder engine getting on for 20 years old is still remarkable. Few cars achieve this
even now without forced induction. It was at the time also the lightest weight production engine for its specific output.
In his Top Gear interview Peter Wheeler said that the 75degree flat-plane crank engine was the same as
a then current F1 engine up to the cylinder heads, and that although Lexus probably wouldn't buy it for
its refinement it was 'a very sporting engine indeed'. Sums it up for me.
I suspect most owners would agree. It will routinely rev to 7200rpm; I suspect you wouldn't want to do that too often with an S6.
To produce nearly 100bhp per litre (from a well fettled Red Rose anyway) from a naturally aspirated
2-valve per cylinder engine getting on for 20 years old is still remarkable. Few cars achieve this
even now without forced induction. It was at the time also the lightest weight production engine for its specific output.
In his Top Gear interview Peter Wheeler said that the 75degree flat-plane crank engine was the same as
a then current F1 engine up to the cylinder heads, and that although Lexus probably wouldn't buy it for
its refinement it was 'a very sporting engine indeed'. Sums it up for me.
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