Usually dual plenum will have a crossover tube so no need for two MAP sensors, also if the TB are synced and you have good compression they will be pretty close anyway. If you run dual O2 sensors you can trim by bank if there are some minor differences between the two banks.
Thanks.
No reason I can't add a cross over tube. Plenum chamber to plenum chamber. SWAG ( scientific wild azzed guess) what size tube is sufficient? 5.3 liters so 2.75 per plenum
mdshaw said:A Jaaaag V12 would be cool. What is it going into? Have been watching all the old Top Gear episodes & lots of Jaaaag V12's on there.
XJS race car. No street use. ( well maybe once I'll take it to the local Thursday night car show at the local drive in.
I think the crossover on the fancy LS manifolds is about 3/4" id
Stampie (FS) said:I'm pretty sure Chevy throttle bodies are way to powerful for a Jag V12. Might want to look at some Smart car ones.
I've been thinking of just using the Chevy sensor on the Jaguar. I'll have to get one to see how much work it is to adapt. The flaw with Lucas is getting it to understand analog instead of digital.
I doubt a German design on a French built car would be any help at all.
The Jaaag sensor may work as is, the TPS is still just an analog resistive device, a throttle actuated potentiometer. As long as it can work with a 5v feed and is relatively linear, it should work fine.
From what I remember the MS ecu works really well with GM sensors. But again that was @15 years ago. It also worked very well with Honda sensors, except the distributor.
In reply to frenchyd :
Will it be at the 2021 Challenge?
In reply to mdshaw :
I'll be doing my own version of the challenge. It's more than a 3000 mile round trip. If I came by myself we are still talking about a lot of expense but If my wife came it would take more than twice as long and a massive expense.
A drag race is pretty much a drag race ( altitude difference) and I'll try to find an autocross as similar to the challenge as possible.
It won't count but maybe other locals will join me?
frenchyd said:yupididit said:frenchyd said:yupididit said:Are they dbw or linkage?
Linkage.
Use one TPS. Make sure both throttle bodies open the same amount at given throttle.
Which MS are you using?
MS1.
Because I want to see this succeed without excuses will a MS1 work for this? I'm asking the more knowlegable MS people out there.
MS1 would have to be hardware version 3.0 or 3.57 because 2.2 must have an optional board to run more than 4 injectors.
MS2 3.57 would be best - more idle control, better rpm control resolution, 16x16 fuel table compared to 12x12, MAP fuel load.
Here is the link to the official diyautotune.com page that shows the differences in a nice easy to understand spreadsheet.
In reply to frenchyd :
I hope you can make it. We just moved to Florida & not too far from Gainesville so I want to go just watch. Everything I have is over budget. Although my son's roommate just crunched his Civic & I do have a good high mileage K24.
Do you have an HE head? Do you have manual or TH400?
I've always been a closet V12 fan but thought they were just too expensive & a turbo Honda is more than adequate now that they spin the correct direction.
A 3.57 board is very similar to a v3.0 board, the biggest difference is the use of surface mount components on the 3.57.
That makes the v3.0 board a better choice for non-standard installs, because you can fold, spindle, and mutilate that one easier.
I'd consider a MS3 as it has more I/O for the extra cylinders.
Fuel only could be a MS1 easily but if you're going to run ignition too MS3 would be my choice.
I would do wasted spark with 6 coils and no distributor. Assuming this is an even fire motor?
MS3 can do that with one hand, room for lots of other features that may be valuable. (Plus on-board logging)
Is that the same distributor used on the 6? If so they have a very poor reputation and probably best removed from the equation.
Spark control and strength are both big factors on a boosted motor. Wasted spark will give you the ignition energy to fire a larger gap.
I would use modern High impedance injectors too.
E85 would take some of the load off the cooling system as well.
No I don't have the HE head. That does not make as much power as the early Flathead does. Doubt me? Look at the horsepower of an HE compared to the early (1971-1980) engine. Same power!! But wait. The early engines had 7.8-1 compression while the HE has 12.5-1 compression. Higher compression should make more power, right?
As far as expensive, I paid $500 for a rust free Southern California Relatively low mileage XJS. ( with a lot of goodies included ). Nice interior, etc.
That's a 1984 HE but I have plenty of motors so I'll yank those heads and pistons off and put the flatheads and pistons in that block. ( most flatheads have the bad transmission ( ( Borg Warner )) with a different bolt pattern that does not take the Turbo 400 transmission or any GM manual gearbox ) 
12:1 compression!
I hope you have the lower compression motor...
Check the cam overlap. A high compression motor may have a lot of overlap (Intake closing late too). Boosted motors don't want any overlap. My 300+ HP Volvo RedBlock project has 0° overlap thanks to Mr Dema Elgin.
Whats the displacement and stock power rating?
In reply to bentwrench :
Same camshaft both engines. Sooo mild, it's designed for old men and their golf clubs. But it's cheap and very fast to regrind the cams from the stock .375 lift and short duration. Seriously you can replace both camshafts in half the time it takes on a Chevy V8
It's 326 cu in for 1971-1992 and 366 cu in until 1997
Horsepower is different depending on who's specs. The 1971-1974 on carbs it was 244 DIN net hp US. 266 rest of the world. Then with EFI it went to 262 US 299 the rest of the world. Finally it went to 318 and 358 rest of the world. ( realize those are net numbers)
. For information a Chevy 454 was 230 SAE net which is slightly smaller than DIN
In reply to frenchyd :
The big benefit of HE was mileage then?
You're going to stir up Stampie with Chevy comments like that.
In reply to mdshaw :
Naw it's like the kid in 3rd grade that always brags about how his dad is the E36 M3. Till one day you see his dad and he's a normal fat middle age guy with a receding hair line. Then you just ignore the kid because he doesn't know anything better.
mdshaw said:In reply to frenchyd :
The big benefit of HE was mileage then?
You're going to stir up Stampie with Chevy comments like that.
Gas mileage and smog. California changed its smog rules and to meet them Jaguar had to change from a performance first priority to a clean engine.
for the street the Honda is definitely more practical. For the race track? The Jaguar is built like a tank. And has no vices.
wvumtnbkr said:frenchyd said:wvumtnbkr said:Why would you need inputs from 2 throttle bodies? Are they gonna be independent?
yes a Jaguar V12 has two. One for the left side and another for the right. Just like Ferrari does and Aston Martin, etc etc
I realize they are seperate. The point is: are they gonna open the same amount at the same time? If so, 1 signal will work just fine.
He could always check that with a maf by dataloging maf vs tps first on one bank, and then the other, or preferably with two identical mafs at the same time. Note: for the above you would want to datalog from only one tps, the one whose signal you are sending to the MS.
In reply to Stampie (FS) :
Well I have repeatedly said I'm fat. But I do have a full head of hair.
In reply to JBinMD :
Hey I've solved my problem. One of the extra's I got with the car is a complete 6.0 intake set. With digital output for the MAF. Everything earlier is analog.
bentwrench said:A 3.57 board is very similar to a v3.0 board, the biggest difference is the use of surface mount components on the 3.57.
That makes the v3.0 board a better choice for non-standard installs, because you can fold, spindle, and mutilate that one easier.
I'd consider a MS3 as it has more I/O for the extra cylinders.
Fuel only could be a MS1 easily but if you're going to run ignition too MS3 would be my choice.
I would do wasted spark with 6 coils and no distributor. Assuming this is an even fire motor?
MS3 can do that with one hand, room for lots of other features that may be valuable. (Plus on-board logging)
Is that the same distributor used on the 6? If so they have a very poor reputation and probably best removed from the equation.
Spark control and strength are both big factors on a boosted motor. Wasted spark will give you the ignition energy to fire a larger gap.
I would use modern High impedance injectors too.
E85 would take some of the load off the cooling system as well.
What we have to remember is I'm doing this on a challenge budget of $2000 right now I stand at $692.
Total horsepower is going to be only a number on the Dyno. My real goal is wheel to wheel racing. The drag race time and autocross times are pretty trivial to me. I'll publish them good bad or ugly. And send some pictures along for others to judge.
Oh, as far as the distributor, no it's a 12 cylinder distributor not the Six very good reliability if maintained. See it needs to be oiled periodically and almost never is. Plus the vacuum advance could be 45 years old and probably needs replacement.
dean1484 said:How are you handling ignition? I think you should forgo TPS and use a MAP sensor versus RPM to tune it. You are going to need to know the MAP anyway to tune with boost. I would put a separate MAP on each Mansfold to see what both sides of the motor are doing. I would have to think about if I would average the two for the MS and Wright somthing that then monitored the two for variance so in case you had a problem with one side and the MS was reading low boost on half the motor when there was full boost on the other half but was not getting enough fuel or not enough timing pulled causing bad things to happen. You could just take vac/boost from both sides to a T connection to the MAP. Put a big enough crossover and you then don't have to worry about this. Thinking more about this I would definitely do this. It would make tuning much easier.
IMO this is the biggest problem with him tuning his engine setup. Basically he has two separate straight sixes as far as breathing goes. He could either make sure that both sides are identical in every respect and nothing changes (although something nearly always changes), or he could run the engine with two separate MSs. If *anything* changes while the engine is being run from one MS (say a vacuum leak, burned/bent valve, one turbo/wastegate/bov starts acting up, boost leak, manifold runner cracks, etc) then one side or the other will be getting the wrong amount of fuel. Are there any ways to overcome that problem other than an intake crossover pipe or running two MS systems?
In reply to frenchyd :
V12 cams come out that fast huh? I thought removing the valve cover on these was a PITA.
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