Classic Mustangs List Archive

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Mail From: chrisstephens (Chris)

I'm installing a Kenne Bell and have a C-4 transmission. Where should I get
a vacuum source for the blower? Should it be on the boost or vacuum side?

Another though and question is, The C-4 uses vacuum to sense when to shift.
I suspect it senses the lower vacuum, and goes to the next gear. While I'm
in boost will it see higher vacuum on the low pressure side than it did
before? Any thoughts on whether or not it will shift right?

To make this a legit question on the Tweecer side, should I move my ACT to
the boost side also? My thought on this is that it would see the temp rise
then retard ignition and add more fuel. What do you think?

Chris

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Mail From: w427 (David)

Replies in-between.

Chris wrote:
> I'm installing a Kenne Bell and have a C-4 transmission. Where should I
> get a vacuum source for the blower? Should it be on the boost or vacuum
> side?

I presume you meant vac for the tranny? Tap the manifold, but you need
to fit a pressure bypass (one-way valve and restrictor) to the vac line
to prevent the tranny vacuum modulator from seeing any boost pressure.
Simple, though.

> Another though and question is, The C-4 uses vacuum to sense when to
> shift. I suspect it senses the lower vacuum, and goes to the next gear.
> While I'm in boost will it see higher vacuum on the low pressure side
> than it did before? Any thoughts on whether or not it will shift right?

In stock form, it uses RPM's, throttle position and vacuum to judge load
and therefore the shift points. It should shift fine if in proper
condition and adjustment but you'll be capable of more power than stock.
I'd suggest looking at this thread
<fordmuscle.com/phpBB/viewtopic.php?topic=9911&forum=13&34>
to be sure it's up to the task and with the proper mods for
supercharging. C4's are great trannies from stock to over 1000hp but
must be built for the level of performance. Fortunately that's
relatively cheap and doable in the home garage.

> To make this a legit question on the Tweecer side, should I move my ACT
> to the boost side also? My thought on this is that it would see the temp
> rise then retard ignition and add more fuel. What do you think?

Absolutely. TwEEcer should have all this info for you. Be sure you
follow their recommendations for best performance and safety.

> Chris

This sounds like serious fun! I'm happy to try helping, but call
Kenne-Bell (909) 941-0985 and STKR (TwEEcer)281-579-0102 for the final
word. They should have enough help for you that you shouldn't be
'wondering' about anything.

David

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Mail From: chrisstephens (Chris)


Yep, that's what I meant vac for the tranny.
The C-4 is a B&M built one I've been running for a year or two now. It's not
built to the max
but it should easily handle the 350ish HP I'll be throwing at it. I'll check
the link in detail.

This is a 70 Mustang I've converted to EFI. I have a 92 Mustang A9L, C-4
transmission and am installing a Kenne Bell.
I've got a 90mm Lightning MAF, 42lb injectors, and installed/ tuned them
naturally aspirated so that I can install the blower.
I had to build brackets and such to spin the water pump the right way. The
pump is long nose non reverse.
A reverse flow won't fit the timing chain cover that I need to fit the oil
pan that clears the suspension. Also the KB I have
is for a long nose pump. I've got the brackets built now and am starting to
slap on the blower.

I was concerned about the transmission and thought it shifted by vacuum
only. That's just one less thing to worry about.

So now I have to do the vacuum side of things. I plan on putting the Fp
regulator, and J&S knockguard on the boost side.
The power brakes, transmission and crankcase vent is going to
the low side. According to a few peeps on the Tweecer list, this is the way
to go with the trans.
One reason is that they have had problems blowing the hose off.

As far as The ACT, I'm thinking about tapping the
KB high side for the ACT. What sort of temps should I expect?
I've got the TwEECer stuff down pretty good. The Boost thing however is new
to me.

I can't get Kenne Bell to answer E-mail or the phone. I gave up and bought a
used kit.
The peckerheads won't sale to the public, or answer questions. Great
product though.
With a Combo like mine, they don't make a plug and play kit so I guess I
have to wing it myself

Chris




Thanks again,
Chris
David wrote:
> Replies in-between.
>
> Chris wrote:
>> I'm installing a Kenne Bell and have a C-4 transmission. Where
>> should I get a vacuum source for the blower? Should it be on the
>> boost or vacuum side?
>
> I presume you meant vac for the tranny? Tap the manifold, but you
> need to fit a pressure bypass (one-way valve and restrictor) to the
> vac line to prevent the tranny vacuum modulator from seeing any boost
> pressure. Simple, though.
>
>> Another though and question is, The C-4 uses vacuum to sense when to
>> shift. I suspect it senses the lower vacuum, and goes to the next
>> gear. While I'm in boost will it see higher vacuum on the low
>> pressure side than it did before? Any thoughts on whether or not it
>> will shift right?
>
> In stock form, it uses RPM's, throttle position and vacuum to judge
> load and therefore the shift points. It should shift fine if in
> proper condition and adjustment but you'll be capable of more power
> than stock. I'd suggest looking at this thread
> <fordmuscle.com/phpBB/viewtopic.php?topic=9911&forum=13&34>
> to be sure it's up to the task and with the proper mods for
> supercharging. C4's are great trannies from stock to over 1000hp but
> must be built for the level of performance. Fortunately that's
> relatively cheap and doable in the home garage.
>
>> To make this a legit question on the Tweecer side, should I move my
>> ACT to the boost side also? My thought on this is that it would see
>> the temp rise then retard ignition and add more fuel. What do you
>> think?
>
> Absolutely. TwEEcer should have all this info for you. Be sure you
> follow their recommendations for best performance and safety.
>
>> Chris
>
> This sounds like serious fun! I'm happy to try helping, but call
> Kenne-Bell (909) 941-0985 and STKR (TwEEcer)281-579-0102 for the final
> word. They should have enough help for you that you shouldn't be
> 'wondering' about anything.
>
> David
> _______________________________________________
> Classic-mustangs mailing list
> (email redacted)
> lists.twistedpair.ca/mailman/listinfo.cgi/classic-mustangs
>
> Visit the Classic Mustang Wiki! sauce.donair.org/~cm/

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Mail From: w427 (David)

I think someone on that list has other problems if they lose vac lines
at anything under 10psig; and it doesn't sound like you're planning
anything near that. Besides, zip-ties and ratchet clamps do wonders
above that level. Additionally, if you're using a boost bypass in the
line your internal pressure is lower still. I'd take some of that with
a grain of salt... call B&M.

Anyway, one tranny test you can do is to remove the modulator vac line
and leave it open. Give it a test drive and see how it shifts. If it's
firm and well timed even at WOT - you should be fine. I still vote for
the high side with a bypass to be sure you get properly timed and full
force shifts as the low side vac may trick the tranny into thinking
you're not on the power as much as you really are. Remember - you are
going to make more power at part throttle than you did at full throttle
before boosting, yet the tranny still expects lower power at part
throttle. Check with B&M on this - but perhaps you see where I'm going
with it - or maybe it's clear as mud now! lol

As far as temps, that primarily depends on the pressure ratio you plan
to run and the supercharger RPM's it will take to do that for your
engine combo. You can make an educated guess using the efficiency
charts for the unit you're using; and a dyno chart or VE graph for your
engine helps a lot. I have charts for Eaton SC's and such on-hand but
not the KBs. Perhaps a quick web search will turn them up. Are you
planning an air/water charge cooler under it? At the low boost levels
you're probably using it's likely unnecessary.

We just finished turbocharging my son's Honda D16A backup engine last
week and will finish base tuning this week when I get the wide-band O2
sensor going, but we're already in the 10-12psig range on pump gas and
everything vac is just push-on. We're calculating right at double the
factory horsepower and the clutch is trying to slip and smoke - which we
expected. Next month's dyno run will tell all. The Neon his bud is
wheeling is now at 17-18psig and no special concerns there either -
however the ports are flanged and clamped for insurance. Compared to a
blown classic iron V8 Ford, these things are like cute go-carts on
steroids. Fun stuff though!

David

BTW - in what part of the country are you located?


Chris wrote:
...
> The power brakes, transmission and crankcase vent is going to
> the low side. According to a few peeps on the Tweecer list, this is the
> way to go with the trans.
> One reason is that they have had problems blowing the hose off.
...
> As far as The ACT, I'm thinking about tapping the
> KB high side for the ACT. What sort of temps should I expect?

This read-only message was archived from a public mail list.
Mail From: chrisstephens (Chris)




David wrote:
> I think someone on that list has other problems if they lose vac lines
> at anything under 10psig; and it doesn't sound like you're planning
> anything near that. Besides, zip-ties and ratchet clamps do wonders
> above that level. Additionally, if you're using a boost bypass in the
> line your internal pressure is lower still. I'd take some of that
> with a grain of salt... call B&M.

Yea, I've gotten bad advise before. This is a post from someone that sumed
up the thinking on the TwEECer list,
"Transmissions that use a vacuum modulator usually only rely on this for
part
throttle shift scheduling and firmness (line pressure reduction when in
vacuum and shifting earlier). Once the transmission sees no vacuum or boost
it reverts to the governor for shift scheduling and goes to full firmness
according to valve body accumulators (or lack thereof with typical shift
kits) and line pressure. Therefore, it really shouldn't matter where you
get the vacuum signal from since most vacuum modulators stop at 0 inches of
vacuum and wouldn't act any different to boost. I would put it between the
throttle body and the supercharger so you never have any positive pressure
and risk blowing the line off the transmission (just an annoyance and hose
clamps are ugly)."




> Anyway, one tranny test you can do is to remove the modulator vac line
> and leave it open. Give it a test drive and see how it shifts. If
> it's firm and well timed even at WOT - you should be fine. I still
> vote for the high side with a bypass to be sure you get properly
> timed and full force shifts as the low side vac may trick the tranny
> into thinking you're not on the power as much as you really are.
> Remember - you are going to make more power at part throttle than
> you did at full throttle before boosting, yet the tranny still
> expects lower power at part throttle. Check with B&M on this - but
> perhaps you see where I'm going with it - or maybe it's clear as mud
> now! lol

I'm with you... Should I use one of those inline one way valve jobs I've
seen on Chevy brake boosters?


> As far as temps, that primarily depends on the pressure ratio you plan
> to run and the supercharger RPM's it will take to do that for your
> engine combo. You can make an educated guess using the efficiency
> charts for the unit you're using; and a dyno chart or VE graph for
> your engine helps a lot. I have charts for Eaton SC's and such
> on-hand but not the KBs. Perhaps a quick web search will turn them
> up. Are you planning an air/water charge cooler under it? At the
> low boost levels you're probably using it's likely unnecessary.

I'm expecting somewhere between 8 and 9 psi.Possibly 10 because my crank
pully is sightly larger than the stock for this kit. I've also got 90mm
intake trac from the filter to the intake with only 1 90 degree bend. MUCH
less restrictive than stock. I cut a hole in the passengers side inner
fender and ran the intake straight out. I may build a fiberglass pod around
the filter and bolts in in such a way that makes use of the "vent" on the
front of the 70 Mustang. Right now I just have the filter sticking out under
the fender.


> We just finished turbocharging my son's Honda D16A backup engine last
> week and will finish base tuning this week when I get the wide-band O2
> sensor going, but we're already in the 10-12psig range on pump gas and
> everything vac is just push-on. We're calculating right at double the
> factory horsepower and the clutch is trying to slip and smoke - which
> we expected. Next month's dyno run will tell all. The Neon his bud is
> wheeling is now at 17-18psig and no special concerns there either -
> however the ports are flanged and clamped for insurance. Compared to
> a blown classic iron V8 Ford, these things are like cute go-carts on
> steroids. Fun stuff though!

I'm almost ashamed to say I like them to. It's just amazing how much power
you can get out of these small engines. It just dosn't compare to classic
iron to me though. I just wish I could make mine handle as well as the
cheepest Honda :-)

> BTW - in what part of the country are you located?
I'm in Lawrenceville GA. Just north of Atlanta on 85. Where are you?

>
> David
>
> BTW - in what part of the country are you located?
>
>
> Chris wrote:
> ...
>> The power brakes, transmission and crankcase vent is going to
>> the low side. According to a few peeps on the Tweecer list, this is
>> the way to go with the trans.
>> One reason is that they have had problems blowing the hose off.
> ...
>> As far as The ACT, I'm thinking about tapping the
>> KB high side for the ACT. What sort of temps should I expect?
> _______________________________________________
> Classic-mustangs mailing list
> (email redacted)
> lists.twistedpair.ca/mailman/listinfo.cgi/classic-mustangs
>
> Visit the Classic Mustang Wiki! sauce.donair.org/~cm/