Supercharged AJP8. one last step!
Discussion
Initially I ran around the 9 psi level and got 497 on the dyno. Air charge temp was around 21 degrees with the chargecooler. Without it, the temp would rise very quickly indeed.
Since then the boost has gone upto around 11psi and I reckon with the new setup we'll get a another couple of psi.
The engine John experimented on was running around 10.5 ish CR as well and that had a lot of detonation problems because of the CR, cam overlap issues and wrong piston design. It struggled to get much above 420 bhp IIRC. The engine was a similar spec to mine but after this experience, we lowered the CR to around 9.5 and changed the cam for a hybrid 218 road cam on my engine.
If you don't have a blow off valve it can cause some real issues. The pressure in the plenum can build up to over 20 psi. On mine the 5mm thick ally plate used to flex. It can then break any seals, or force the throttles open or even blow out the throttle body seals. The reason is the blower produces a very large volume of air and that has to go somewhere. It can also cause issues with lean out when the pressure builds and then forces past the throttles.
The car used a DTA ECU with mapping based on manifold pressure. Fuel consumption on track was around 2 mpg. As the car is an 86, I don't have to worry about emmissions which is also a bit of a challenge as it runs a tad on the rich side to make sure there is no detonation.
The car was featured in PPC a couple of years ago... http://www.shengltd.com/tvrextras/docs/WedgeinPPC....
Since then the boost has gone upto around 11psi and I reckon with the new setup we'll get a another couple of psi.
The engine John experimented on was running around 10.5 ish CR as well and that had a lot of detonation problems because of the CR, cam overlap issues and wrong piston design. It struggled to get much above 420 bhp IIRC. The engine was a similar spec to mine but after this experience, we lowered the CR to around 9.5 and changed the cam for a hybrid 218 road cam on my engine.
If you don't have a blow off valve it can cause some real issues. The pressure in the plenum can build up to over 20 psi. On mine the 5mm thick ally plate used to flex. It can then break any seals, or force the throttles open or even blow out the throttle body seals. The reason is the blower produces a very large volume of air and that has to go somewhere. It can also cause issues with lean out when the pressure builds and then forces past the throttles.
The car used a DTA ECU with mapping based on manifold pressure. Fuel consumption on track was around 2 mpg. As the car is an 86, I don't have to worry about emmissions which is also a bit of a challenge as it runs a tad on the rich side to make sure there is no detonation.
The car was featured in PPC a couple of years ago... http://www.shengltd.com/tvrextras/docs/WedgeinPPC....
Edited by shpub on Tuesday 7th February 14:30
Edited by shpub on Tuesday 7th February 14:32
Thom said:
Have you folks replaced the standard NA pistons on your engines with conical-shaped pistons as used in turbo engines?
I would be concerned with thermal expansion on the standard NA pistons..?
mine has 9.25:1 CR achieved by forged FI spec (dished) racing pistons from the states and cometic gaskets.I would be concerned with thermal expansion on the standard NA pistons..?
Gazzab said:
My cometic gaskets failed on my engine. Apparently it was down to the gasket.
... yeah, thanks for that, just what i wanted to hear 
Jury's out on which of us is the "unluckiest" at the mo.
I will have to, ahem, test my car "vigorously and extensively" as soon as i get it back, in order to force any potential failures early in the engine build warranty period
well at long last I went to Emerald yesterday and got the supercharged AJP mapped. The engine and car performed perfectly. The guys at Emerald are brilliant and I am really please with the results they dont overcomplicate things and waffle, they just know exactly what they are doing.
To completly map their ECU with 3 different maps, 1st map 97 octane, 2nd map 95 octane, 3rd map novice drivers safety map? (mine)
£305.00+vat!!!!!. Car runs better than ever 900RPM in 5th and it just pulls and pulls. Floor the throttle in any gear and the performance is stunning.
Figures are as folllows: 535bhp at 6250rpm. 460ftlbs torque at 5354rpm didnt want to take it any higher as the engine has only done 500miles and only has semisynthetic oil at present. The supercharger is producing 6psi of boost. No detonation problems or overheating even though the car was on the rollers for 8hrs. I think with some differnt pullies careful mapping at the higher RPM maybe 600bhp could be possible. One unexpected plus point is the throttle responce, its instant no lag it picks up like a bike engine (Emeralds comments not mine)
Once its run in I will try and get some performance figures. So if it all holds together then I think its been a worthwhile project.
To completly map their ECU with 3 different maps, 1st map 97 octane, 2nd map 95 octane, 3rd map novice drivers safety map? (mine)
£305.00+vat!!!!!. Car runs better than ever 900RPM in 5th and it just pulls and pulls. Floor the throttle in any gear and the performance is stunning.
Figures are as folllows: 535bhp at 6250rpm. 460ftlbs torque at 5354rpm didnt want to take it any higher as the engine has only done 500miles and only has semisynthetic oil at present. The supercharger is producing 6psi of boost. No detonation problems or overheating even though the car was on the rollers for 8hrs. I think with some differnt pullies careful mapping at the higher RPM maybe 600bhp could be possible. One unexpected plus point is the throttle responce, its instant no lag it picks up like a bike engine (Emeralds comments not mine)
Once its run in I will try and get some performance figures. So if it all holds together then I think its been a worthwhile project.
Well done Paul, excellent news, really pleased for you.
I knew it could be done and you went about it the right way in keeping it simple and not over complicating it by worrying about if x or y happens or trying to build something bullet proof that ends up bleeding all your funds and enthusiasm and sitting dormant for years.
And the fun don't stop yet.... make sure you can monitor the intake temps easily I think you can set alarm limits within the emerald to light the MIL?? Also might be worth setting up a knock sensor, I would have thought the emerald could take the input or fit a stand alone unit.
Fantastic achievement, most powerful (verified) AJP8???
Look forward to meeting you at Chatsworth if you can make it.
Rich.
I knew it could be done and you went about it the right way in keeping it simple and not over complicating it by worrying about if x or y happens or trying to build something bullet proof that ends up bleeding all your funds and enthusiasm and sitting dormant for years.
And the fun don't stop yet.... make sure you can monitor the intake temps easily I think you can set alarm limits within the emerald to light the MIL?? Also might be worth setting up a knock sensor, I would have thought the emerald could take the input or fit a stand alone unit.
Fantastic achievement, most powerful (verified) AJP8???
Look forward to meeting you at Chatsworth if you can make it.
Rich.
Boosted Cerb said:
And the fun don't stop yet.... make sure you can monitor the intake temps easily I think you can set alarm limits within the emerald to light the MIL?? Also might be worth setting up a knock sensor, I would have thought the emerald could take the input or fit a stand alone unit.
Rich.
Do you run an Emerald on your car?Rich.
We were monitoring the intake temps during the mapping and at one stage they rose to 60 degrees (45 was the norm) in the plenum after several hours on the rollers but it didnt appear cause any knock problems which we monitored very carefully.
I will monitor the temperatures with my laptop over the next few weeks and see what a session of spirited driving on the road makes them rise too. What is nice is you don't have to thrash the fock out of the engine to get the performance. It has a soft cut at 6250rpm and a hard cut at 6500rpm which is much lower than the 7250rpm they normally have so will hopefully help preserve the engines internals.
I must look on the ignition map and see what advance they are running. I was using optimax fuel. It knocked with the standard 4.5 map but they backed the timing off by a few degrees and it solved the problem. It now has a complete custom map that has virtually no resemblance to the original AJP8 map.
I'm not 100% sure of my CR. I opened out the combustion chambers to 52cc which was quiet a bit of metal to remove. Its also running the latest Bosch multihole injectors and has the one off throttle bodies...maybe these have helped?
I suspect though that a lot will be down to the mapping and as I said before the Guys at Emerald just know exactly what they are doing, I cannot recommend Dave and his partners enough.
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