boxer on a dyno

Keep in mind the 365BB has a higher redline 7500 vs 7000 for the 512BB for those cams you'll need to rev the 512 motor higher, I would look more into a 512BBLM cam profile or something a bit less radical.

The factory wsm states the 512BB has 360hp which should equal around 290-300 at the wheels, 267 isn't bad for a BBi

 

Thanks Mark, I was thinking about the WUR calibration not liking the cam choice then I thought about larry fletcher who rebuilds the distributors and WUR's for a living. If he can calibrate them to spec why couldnt he do something custom for my application. Ill have to give him a call and see what he says. IF I can make the car perform the way I want it too and retain the CIS I would be happiest. I still keep flip-flopping over the EFI conversion because Im a purist but I did see in the 512TR thread that the stock fuel rails and injectors would work perfectly in my boxer, eliminating the need for custom rails and non-ferrari parts....its just another thought if I went that route. I think either way I need to replace my injectors and sort the car out on the dyno, find the missing HP and then get my hands on some cams.

 

Larry Fletcher to the rescue again, the regulators can be adjusted to work with my mods if the need be. Now I have to settle on a cam choice.

 

365BB 344HP@7200rpm, 7700 redline
as tested weight with 120l fuel, 3417lbs - d'oh just like a 512bb not a 1000lbs lighter like some say.
512BB 340HP@6200rpm, 7000 redline
512BBi 340HP@6000rpm, 7000 redline, my car weighs 3400lbs too, weighed it last summer.

We need to get a few boxers together for a race, ill squeek 340HP out of mine soon, even more with cams!

 

I hope Larry can make it work but…..

I took a quick look at web grinds for 911 since they have the same injection system and I know the porsche guys have tried everything.

2 grinds popped out
one is .484/.450 lift (intake/exhaust) and 244/232 duration at .05” and is labeled in all caps, not recommended for stock injection.

The second one is .485/.452 lift and 238/226 duration at .05” lift and labeled special to work with stock injection.

As a reference the early ferrari 2v cams are about 240 duration at .05 and the late ones are 220 at .05” on both intake and exhaust, so a lot more total duration then the porsche set-up. I’m guessing you are going to have problems, but maybe Larry can work some magic.

I played around on the simulator a little more and I think I’ve got it about right now. I switched to a little more free flowing manifold and added a little more restriction for the CIS. It looks like the cam change alone should be 20 hp if you can get it to work. Then you get another 25 if you remove the CIS, which is about what QV/328s get. If you remove the CIS and keep the stock cam, you gain 25 hp.

I can’t wait to see what you try and what the actual result is!

 

Larry explained that the enrichement diaphram only takes about 5" of vacuum to hold it against the spring pressure before enriching begins. That makes me feel more comfortable about the change, I remember reading around 16" when I was balancing the banks a while back. I know im not out of the woods but there is some adjusting he can do to change the curve on them. I also went to rennlist and looked up 911's yesterday afternoon just to see what they were doing as well but had no luck finding anything as a non-member. Some WUR's have no vacuum source so I asked what if I change to a pair of them from a different car? He's unsure and we dont know exactly how they would enrich other than through the distributor? As an example a 930 turbo uses no vacuum source and only applies enrichment under boost not vacuum so something is different there as well.

 

I have to admit that I know almost less than nothing about CIS so I can't give any meaningful input really.

I was always told that the problem isn't about vacuum or not, it's about reverse pressure pulses at low rpm (cause by valve overlap) buggering with the big mass air plate and not allowing it measure and the problem with big cams is just a question of how hgih you're willing ot set your idle. I’ll ask the porsche guys at work today to see what they know, if anything, but Larry messes with them for a living, so if he thinks he can make it work then maybe he can.

In you 930 example, if there’s no vacuum port I'd assume the WUR is getting mass air info from the distributor, or the distributor is only accepting WUR info above some air flow threshold….that’s the only guess I have.

 

I originally thought (and heard) it was the plate that would bounce due to agressive cams as well but then heard otherwise. Not sure which is correct though but the vacuum drop at the WUR would certianly bugger it up. Both are good arguements, ill keep digging as well.


thanks for the input,

P.

 

Thats very tempting especially with stock 512TR rails and injectors available. The t-bodies can then run straight to the air intakes on the rear deck rather than around the garden path to the CIS distributors. Question, can you measure a t-body opening for a QV engine? Im assuming mine are smaller since they only feed 2.5L each, maybe even a 328 might be better.....mmmm....more research.

 

Straight air runs sound like a good plan to me
(but I do understand wanting to leave it stock)

I never thought about TR rails, but the bore spacing is the same, so I guess they would have to fit wouldn't they?

The 2Vi, QV and 328 all have a 65mm TB as far as I know, even though the hp ranges from 205-260. TB sizing is more about flow (hp) than displacement. 200 hp requires about 200 cfm at 10" flow. A 65mm TB will flow about 250-300cfm at 10", so it's plenty big on a 205hp engine and pretty marginal on a 260 hp engine.

There has a guy claiming gains with a 70mm over bore. He was boring both the TB and the manifold, but had flow bench only numbers, no dyno results. One QV owner did buy the oversize TB only and dyno it, and lost hp...which I guess is what you would expect with the diameters mis-matched (the QV/328 plenum has a 65mm bore in it).

 

Ill have to measure mine and see the difference. I know throttle resonse could get hurt with the larger t-body even port matched. I think with CIS to EFI injector adapters like the porshce guys use would be all thats needed to push the TR rails and injectors in.

 

That is where richening thinks up comes into play. It's easy with EFI, it easy to deal with, you can add fuel based on the rate the TB is opening at, basically just like an accelerator pump on a carb. I had A 62mm x 120mm oval on the QV with the blower and it was as snappy as it could be. With the CIS it's a little harder I think.....but Larry would know.

The one think that’s important with oversize TBs is to use a linkage or cable pivot that is non-linear. You want to less than 1:1 with the pedal near idle and then make up for it up top. A big throttle plate exposes much more flow area at smaller openings, so you want it to move slowly at first or it can be difficult to modulate at low rpm and cruising speeds. The cable mount I had on the monster TB looked like a cam, with about a 2”R at first dropping to about a ¾” radius at the very end.

 

I agree about the cam on the t-body, seen it on many other applications to change the opening rate but im unsure of the boxer set-up since its under the plenum and I can honestly say I havent poked my head under it to see the mechanism - my bad. I should have run the car with and without the airbox assy, I suspect it too is a restriction so I will next time. As for response with a toilet sized t-body goes, you're not being fair since you have boost (which I would love to do and the CIS wont mind).

 

You could be right about the boost, but they do sell that crazy TB as a bolt-on for ford 4.6 engines and the guys seem to love them. I picked it mostly because the shape matched the blower inlet pretty well making the adapter look nice...there's science at work

 

A most interesting thread, I am doing my EO this winter and have been thinking about the efi upgrade. Seems it is either very complicated or with motec quite expensive. If a 512tr fuel rail works that is a plus, would the rest be plug and play, what would be required.

I was thinking about efi with 512 cams as the bbi cams were flattened for the CIS. If the CIS can work with better cams by idling at say 1200 rpm no biggie. Ferrari was probably thinking of a saleable product meeting legislation/emissions with flatter cams and better off idle emissions and driveability. So if a CIS can work with say 512 cams that may be a good simple starting point.

However the intake runners may be optimised for the current cams so any upgrade even with efi may not really work? I will be starting on my car early next year so anyone else's experience and suggestions would be greatly appreciated, either as to upgrade or fully rebuilding/sorting the CIS.

Basicaly the car runs OK but after 25 years it is going to have a good freshening of all the big and little bits so it can hopefully be enjoyed for another 25 years. What dents the budjet will detirmine how far I can go.

 

The 512TR rails will fit if you extend the mount tabs to reach the manifold mount studs since the BBi runners have no provision for this. I called TRutlands and they have no used or new rails so I would have to locate them and probably open my wallet wide for them. $175/pair gets me custom made rails, I can buy 19lb injectors cheap and the motec would be easy. A simple MAP system with 1 TPS rather than having to use two and sync them, I see no point to that. The 512TR rails come with the vacuum regulator too if one could score them used. An IAC is another requirment unless the factory bi-metal fast idle mechanism can be left on and then the O2's. Its not too bad and the gain would be worth it, the cams can then upgraded (in my case during an engine out which is a few years away).

 

1 TPS sounds like the way to go, that's what I'm planning. The Motec is I think the best ECU out there, you can't go wrong with that, get the M800 if you go motec. The haltech is about 1/2 the price and a little more plug and play IMO but because it's plug anf play, it's not as flexible, you need to use the sensors they tell you to, will only read 1 O2 sensor (you don't actually need any if you don't want them, it's a fuel milage thing, not performance) and a couple other limits. I think an IAC of some kind is manditory, motec will will with almost any if you can figures out the correct parameters, haltech uses a GM and you just set the rpm you want and your done.