mark kibort

thanks Erik!

I think a common misconception is that a high strung motor is not useful for street use. If someone wants power, its not uncommon to downshift. sure, climbing hills or passing in the lower RPM range is convienient and is a good feel (that "torqey feel" ) but in the end, it seems most want to have the raw power for passing and "racing", which occurs in the upper RPM range. we are not talking top 95% here , but actually from 4500rpm to redline (upper 30% ) of the RPM range.

when i disabled my "flappy" as it could do , more harm than good if it didnt open, in the 4500rpm range, i found that i never drove the car in the 3500 to 4500rpm range at the track, so it didnt matter. when i did the euro intake and cams, i ended up with the exact same peak torque at 4500rpm, but after that, the gains were over 35hp which was worth it.

im thinking with this mod, the peak torque will probably be the same as removing the flappy, so that big bump in HP in the 3500rpm range will be gone, BUT, if it works out well, the gains to the peak HP range, will bump up 20 to 30hp . I think the stroker gains will be a lot more, for obvious reasons, but i have a feeling this imight be a mod for all 928 motors. again, its just really odd, with all the intake mods being done , that they have alll been for supercharged versions. we just haven't seen that many yet... greg brown's and the Threshie intakes are all ive seen bolt on and they all produced significant gains. (with gregs paying more attention to the "driveability" factors and HP levels down low)

anyway, Its a project. whether illl be able to finish it and be successful, is anyone's guess. the first step is seeing if the runner configuration can be spread out to fit the 928 heads and Han's lower manifold plates. the rest might be a bit easier.

hacker-pschorr

Yes I know - which is why the Subaru BRZ is plagued with reviews that simply say it's under powered.

However....with regards to this topic:

dr bob

You'll quickly notice that the injectors are part of the intake manifold on both cars. You'll likely notice that the 928 fuel rails don't line up with the injector holes for the AM manifold. You'll also find out that "stretching" the legs on the AM manifold will require a bunch of welding/filling and grinding. Where did those injectors fit again? Plan on fabricating fuel rails. Hans may have some solutions that can be adapted from his project, if you get him the right dimensions from where your injector nozzles eventually end up.

Plan on doing the fitting and fixing stuff with the manifold on your mock-up engine in a stand. Else you'll end up with pulleys and brackets held on with Gorilla Tape. Much Easier to fab and fit stuff on the stand. Then drop the whole thing into or onto what you have.

Anyway -- Enough discussion on what it "might" do or "should" do for horsepower. Next Step Is Build It.

mark kibort

Agreed!

However, as far as the injectors... let me know what im missing..
if i re -runner the legs, they are mounting to the Hans manifold adapter, which has the injector mounts, or are you talking about the brackets that are on the S4 intake?? i think so.. good point. there is another welding job right here.

I dont think ill have to re-fab fuel rails , why would the stock ones just mount to the same flanges that the stock manifold uses? something else to look at.. im sure there is more too!

anyway, i agree. ill start and see what i run into.

mk

mark kibort

has anyone looked at the mustang cobra R intake. it looks like the ports are further apart ,no? looks a little lower profile and im sure , big power gains for it as well

below, the mustang, the 928 and the aston martin intake for comparison.

look at the bends and diamter of the 928 intake. say hello to complicated restrictor plate racing!

hacker-pschorr

You know, if you are still "fishing" for a donor manifold....

Have you looked at any custom "sheet metal" intakes for the big block chevy's? They bore spacing would be the same.... a hell of a lot less work than cutting up an entire manifold.

Just a thought.

mark kibort

Thanks, and I've seen a few. i dont think they would have the gains we are looking for, and might be limited to very upper RPM levels. the bore spacing is very weird (you know that US V8 config) But yes, i have the AM intake on the way, so kind of committed to the project. as far as cutting it up... we are just taking it off at the knees. after that, i think its fitting the runners, or modifying the remains that will weld to the manifold adapters and then weld on some fuel injector rail mounts....... mount the ISV, a few breathers, the fuel reg vacuum on the vacuum side of TB and of course the entire MAF, airbox config. which might be the most challenging of all the mods.

V2Rocket

the Ford Cobra R manifold is a little bigger than the Aston would be (100mm bore centers) but still 22mm PER CYLINDER closer together than the 928.

that was a 5.4L DOHC rev-monster that was rated 385hp but really was a little more than that.

definitely agree with Hacker on this...pretty sure i said the same thing in the Ferrari thread.. you can get them in all kinds of runner lengths. runner tuning doesn't really change based on platform - it's all just RPM vs cam timing to get the last push of air in before the valve closes.

you could call up a BBC sheetmetal manifold maker, tell em your idea and give them a manifold gasket and they could tweak their design pretty easily (port shapes and bolt pattern)

mark kibort

you are confusing the old navigator intake, vs this one. the new one was for 2011 to 2014 cars. NOT the 2000 cars. and was for the 5 liter, not the 5.4 liter cars. it was called the "cobra jet intake" but its not the CobraR car..... HUGE DIFFERENCE
https://www.americanmuscle.com/cobra...ld-1113gt.html (only 800 bucks by the way!)

the Cobra typeR that made 385 flywheel hp, was back in 2000 and typicallly, that was what it measured at the wheels. i raced one of the very first ones ever raced in a WCGT race in 2002. these didnt have the same intake im talkng or thinking about.

anyway, the Boss 302 made near 440rwhp and was a rev monster, but made HP of near 420 near the lower revs too. all intake .
the 5.4 liter with this type of intake was making near 485HP.
its not so much about the revs... its about reducing the restriction. its the reason the AM and boss 302 make the power they do. its not anything special in the engine. with a crappy intake, both would make little HP.

V2Rocket

you literally just said cobra R manifold which is what i was talking about, the 385hp 5.4 engine from 2000. and you posted a photo of the well-known 5.4 Cobra R intake...

like this on the outside...


then maybe you didn't race one of those? the Cobra R had that intake inside a big plenum not unlike the AM (but bigger). maybe you were racing a 99-2000 cobra, which was a 4.6L DOHC with a manifold like this:

which looked like this on the inside:


this is the manifold you just linked to.

mark kibort

Sorry, i cant keep all those intakes straight. the bottom line, the intake is extremely important. I was doing some research on those cobra intakes, mustangs, and looking at the bottom ends and heads. so many changes . The bottom line is the base block and head specs. when you have a Aston Martin 4.3L making up to 400rwhp, or 4.7 with near 450rwhp with not much more than an intake difference , it all points to something that has a great chance of making some major HP gains.
also, think of the bolt on intake we did on the Anderson and fan cars... 100hp , with no tuning, using stock ECU settings!
Getting back to the cobra... yes, it looks like the 2000 cobra did have that intake and did have the 5.4 liter, but truth is, the 385hp was a bogus number. its known that all were dynoing that at the wheels. again, look at the engine specs. it was not a pretty layout bore and stroke. the 928 is more over square (vs the cobra R 90mm bore x 105mm stroke! vs 100mm x 78 or 92mm 928 stroke) and more ideal with similar cam lifts, higher compression at 10:1 vs the mustang 9.3:1, etc.

Don't get me wrong, this is going to be a challenge. Fitting this is not going to be an easy path. looking closer, there are challenges. Moving the oil filler, might be challenging. fitting it backward, also might be a challenge.. air filer, putting things in the in the base of the windshield area.
the more i look at it, the harder it looks! I think the mounting to the manifold adapter, might be the easy part.

Imo000

Next post should be of the bought manifold with the chopped of runners.

mark kibort

thats when there is no turning back..... im losing a little motivation based on its size and the effort to have to change the oil filler. i guess that is easy when the extender is used to make the oil filler end up toward the windshield.
the airbox is going to be no small task either, unless i front face it and just run over the radiator like andersons and Fan's intake system. (albeit with only a single intake )

dr bob

Mark --

Find some pictures of Louie Ott's inlet ducting over the radiator. His is ITB but his pre-plenum ducting should give you some ideas. You'll have throttles in that section, along with your airflow/MAF or MAP sensor setup depending on which engine management system you are going to use.

Jerry Feather

With all this modification, refitting and matching intake runners, why don't you just put it on backwards with the intake in the rear?