Engine suggestions...
Discussion
Hi all,
I'm just about to buy a Tuscan race car but it currently has no engine. I have been trying to weigh up whether to put in an AJP V8 as it should have, or an LS3 due to the increased power and reliability. After speaking to the owner about it yesterday though, he said that he had considered putting in a BMW straight six, turbocharged which seemed an odd choice to me. The rest of the car is very, very well specced though, so I imagine he had some good reasons for thinking this.
So this has brought me to think, should I consider any other engine choices for the car? The criteria is (roughly)
- Lots of power (circa 500 bhp would be nice)
- As light as possible
- fairly small
- reliable and not averse to being thrashed in a racing car.
Are there any other good and realistic options out there other than the AJP or an LS3?
I'm just about to buy a Tuscan race car but it currently has no engine. I have been trying to weigh up whether to put in an AJP V8 as it should have, or an LS3 due to the increased power and reliability. After speaking to the owner about it yesterday though, he said that he had considered putting in a BMW straight six, turbocharged which seemed an odd choice to me. The rest of the car is very, very well specced though, so I imagine he had some good reasons for thinking this.
So this has brought me to think, should I consider any other engine choices for the car? The criteria is (roughly)
- Lots of power (circa 500 bhp would be nice)
- As light as possible
- fairly small
- reliable and not averse to being thrashed in a racing car.
Are there any other good and realistic options out there other than the AJP or an LS3?
V10Mike said:
If you want to save some money, why not a good old fashioned iron block SBC? With a decent set of aluminium heads 500bhp is easy with a roller cam, no electronics so you don't have to worry about EMS or harnessses, and the weight is very little more than an LS.
Ah I love electronics though! I'm gunning for launch control, digital dash, 3d mapped ECU and that lot, together with maybe paddle shift gears if/when I can afford it. An iron block would certainly be possible, but I want to keep the weight down as low as possible as it will affect the balance of the lightweight car so much (an LS already needs setting back 6 inches in the chassis).
Boosted LS1 said:
How are you scavenging those turbo's John? Have you a pump in there somewhere?
No pump, the photos don't really show it but there is a fair drop from the oil drains to the sump. The GT ballbearing turbos have a very low oil flow too as they are fed through a 1mm orifice so they don't have the volume of oil to drain like the older plain bearing types.
The bottom end is a standard AJP8 all steel setup as it's very strong and easily up to a lot more power, especially if you can generate it without mental RPMs. The pistons are custom forged jobs designed by me with great assistance from Andy Baker at Accralite. The skirts are now full diameter as the slipper pistons would have no chance under boost and the skirt depth has been increased by a few mm to add stability. The limiting factor is clearance between the crank web and piston skirt at BDC which is very small even on standard AJP engines as they are not described as an F1 bottom end for nothing. The compression has been dropped to 8:1 to allow a maximum boost of around 1.5 bar (22 psi). The head gaskets have been custom made in copper with wire ring seals (Ferriday/TVR Power). I sought advice from Dom at TVR Power on the head sealing and he gave me a useful tip about high power AJP engines. They have a problem with the liners walking around which can really only be cured by wire rings to solidly lock the top of the liner to the head. I also instinctively didn't trust the standard head gaskets under boost having built a few turbo conversion engines before.
Cams are standard which should be OK for the expected RPM range of 2k to 6.6k. The engine management is an Emerald K3 but now running MAP rather than pure TPS as it is on the NA AJP engine, a wideband O2 from techedge is also going in. Injectors are some high impedance Siemens ones which are big enough for 650BHP but probably too small for the output we finally want to achieve these are fed by a pair of Bosch fuel pumps which should be plenty big enough. The plenum shown was a first attempt but I'm having another go in aluminium with the throttle bodies reversed for a lower bonnet height (injectors on the outside). A single 4" throttle body and 2 air/water intercoolers with 2 rads (for the intercooler coolant) on the front and another big one under the boot lid with a couple of big fans on it. The turbos are Garrett GT2860RS with 0.86AR housings which again are limited to about 660BHP but this engine is really just a proof of concept and reliability before we try to turbo my Cerbera next year. Still on a T5 box which will certainly break quite quickly but I'm hoping to go to an T56 if Gearbox man ever replies to my email..
The clutch and flywheel are from Race Proved, the flywheel is their standard lightened one but the clutch is a custom twin plate cerametalic paddle jobby which they tell me has been very well tested on a tuscan racer for a couple of seasons without any grief. The joke is that this engine cost less to build than most are paying for a standard AJP8 rebuild, of course if it blows up the laughs on us but we are quietly confident it will be OK to 600BHP and hopefully we can make 750BHP with bigger turbos and injectors. In my experience revs break engines not power output, at least within reason. If you can generate the power with good mixture and no detonation the engine should be reliable.
Cams are standard which should be OK for the expected RPM range of 2k to 6.6k. The engine management is an Emerald K3 but now running MAP rather than pure TPS as it is on the NA AJP engine, a wideband O2 from techedge is also going in. Injectors are some high impedance Siemens ones which are big enough for 650BHP but probably too small for the output we finally want to achieve these are fed by a pair of Bosch fuel pumps which should be plenty big enough. The plenum shown was a first attempt but I'm having another go in aluminium with the throttle bodies reversed for a lower bonnet height (injectors on the outside). A single 4" throttle body and 2 air/water intercoolers with 2 rads (for the intercooler coolant) on the front and another big one under the boot lid with a couple of big fans on it. The turbos are Garrett GT2860RS with 0.86AR housings which again are limited to about 660BHP but this engine is really just a proof of concept and reliability before we try to turbo my Cerbera next year. Still on a T5 box which will certainly break quite quickly but I'm hoping to go to an T56 if Gearbox man ever replies to my email..
The clutch and flywheel are from Race Proved, the flywheel is their standard lightened one but the clutch is a custom twin plate cerametalic paddle jobby which they tell me has been very well tested on a tuscan racer for a couple of seasons without any grief. The joke is that this engine cost less to build than most are paying for a standard AJP8 rebuild, of course if it blows up the laughs on us but we are quietly confident it will be OK to 600BHP and hopefully we can make 750BHP with bigger turbos and injectors. In my experience revs break engines not power output, at least within reason. If you can generate the power with good mixture and no detonation the engine should be reliable.
Marquis_Rex said:
LS7 or a Super charged Jaguar engine if you want to keep it home grown. Jag 4.2 engine can be coaxed to about 450 bhp with the right intercooling, low back pressure, correct pulley ratio and a modified airbox assembly
Another vote for the supercharged Jag V8 here. Intercooling wise you can just about get by with the standard 'cast in manifold' water/air intercooling assuming a good cooling circuit is in place for these i.e. large volume, good flow rate, well sized radiator mounted in a position with good ambient air supply. As you won't be running the standard Jag ECU though its important to make a good choice when it comes to engine control. You really need something with accurate individual cylinder fuel trim capabilities to ensure correct fueling on all cylinders. This obviously adds to calibration costs as you will need manifolds with lambda bosses at the very least so you can measure the AFR of each cylinder - really you want EGT as well and possibly 4 or 5 gas so you can build a picture of the combustion process but for a race engine calibration simply ensuring correct AFR across all 8 will be fine. Pectel SQ6, Life Racing F88, Solaris S8, MM Marvel 8 and several Bosch Motorsport products will all do the job well - if budget is restrictive a Motec or similar will just about do it but with less control.
Most importantly don't trust general 'aftermarket' tuning opinion on these engines, for the most part (and especialy calibration wise) the 'recognised' safe limits for these engines in terms of boost and spark....... aren't very safe.
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