Why can't 94/95 models be overdriven more than 5%?

95MTSC

Registered User
Seems like it's pretty common knowledge that if you overdrive the blower on a 94/95 model more than 5%, it will ping, so it really shouldn't be done. This generally doesn't happen on the earlier models though.

I'm wondering why that is? Is it that the EEC is much different in the later models? The cam is also much different in these models with the kooky late-closing intake valves (miller cycle?) Or is it something else? Dave D. or any other gurus have some insight? Thanks!
 
The newer style blowers are more efficient so they push more air at the same RPM as the older style, without the gastly temperatures. I also imagine the older style allowed some leak back around the rotors when the pressure built up enough, where as the newer style was less forgiving this way.

Over driving the newer style on an older car also causes alot of problems.
 
Yes it would, and also add a double IC or FMIC while your at it.

Actually, blower over driving on a stock car much over 5% even on the old blowers is asking for trouble.
 
I didn't realize that the issue was with the blower itself for 94/95 models. I thought it was something else related to the 94/95 cars (EEC, cam, etc., etc?)

Seems like even when doing the usual precautions, like making the exhaust flow better, IC fan, etc, the 94/95 cars won't allow much overdriving. Maybe I'm wrong.
 
I didn't realize that the issue was with the blower itself for 94/95 models. I thought it was something else related to the 94/95 cars (EEC, cam, etc., etc?)

Seems like even when doing the usual precautions, like making the exhaust flow better, IC fan, etc, the 94/95 cars won't allow much overdriving. Maybe I'm wrong.

my uncles 95 sc auto with manifold back exhaust,ported exhaust manifolds,double i/c with fan,upgraded fuel system,upgraded intake components wouldnt accept more than a stock 89-93 pulley.5% pulley dropped rwhp by 20,same dyno,same day.stock cam is likely cause.
 
The biggest thing about the '94/'95 EEC's (ECU) is the fact they apply learned adaptive adjustments even when its in open loop (WOT or close) which supposedly a HUGE pain to work around unless you "tune" the car in that range for better performance and to accept modifications you done.

The older EEC's where a bit more forgiven because adaptive was only applied during closed loop (part throttle), then went strictly by what was in the configuration tables in the EEC in open loop.

Dave D could explain better than me as I'm still learning about tuning etc.

I thought initially you where just asking about the 94/95 blower.. sorry for the confusion.
 
my uncles 95 sc auto with manifold back exhaust,ported exhaust manifolds,double i/c with fan,upgraded fuel system,upgraded intake components wouldnt accept more than a stock 89-93 pulley.5% pulley dropped rwhp by 20,same dyno,same day.stock cam is likely cause.

Yes - that's exactly the type of thing I'm referring to! I wonder if swapping cams would bust down that wall?
 
It's more likely the restrictive exhaust and heads that do not allow for max overdrive.

I have been discussing this with jludorf and indirectly Dave D. Free up the flow in the heads and exhaust and the added OD should not be a problem. The added efficiency from the newer blower and greater boost capability is too much for a factory motor to handle.
 
The late model blowers do generate heat just as much as the early ones. Getting your blower ported (properly) helps a lot.

The 94 has higher compression and is therefore more sensitive to boost and the stock exhaust is more restrictive than the early model cars but the exhaust is probably not a major factor.

Camshaft - not really.

The 94 has a much more sensitive knock sensor system. Ford was scared silly about head gaskets in the 94's and so they made the EEC a lot more aggressive with it's protective measures.

Once you install ported heads that have combustion chamber modifications that will resist detonation, then you can be more aggressive with the tune and will be rewarded with power.

I've seen high boost and 300rwhp on several stock 94's with no real problems but the right pieces have to be in place to make it work.

The adaptive fuel strategy in the early cars operates in the same way as the late model ones. There is no learning at WOT.
 
Oooopppssss!

I thought I had read that the newer EEC's used adaptive logic even at WOT hence the reason they where a pain to tune compared to the older EEC's. Well, gotta keep going at the books I guess, meanwhile me keep big mouth shut.

Probably explains why I don't get answers to things as its obvious alot of folks have me on the "ignore" list :D

Oh well, catch y'all around while I keep being dumb ;)
 
The late model blowers do generate heat just as much as the early ones. Getting your blower ported (properly) helps a lot.

The 94 has higher compression and is therefore more sensitive to boost and the stock exhaust is more restrictive than the early model cars but the exhaust is probably not a major factor.

Camshaft - not really.

The 94 has a much more sensitive knock sensor system. Ford was scared silly about head gaskets in the 94's and so they made the EEC a lot more aggressive with it's protective measures.

Once you install ported heads that have combustion chamber modifications that will resist detonation, then you can be more aggressive with the tune and will be rewarded with power.

I've seen high boost and 300rwhp on several stock 94's with no real problems but the right pieces have to be in place to make it work.

The adaptive fuel strategy in the early cars operates in the same way as the late model ones. There is no learning at WOT.


Thanks SuperDave! That answered a lot of questions :cool:
 
Yes it would, and also add a double IC or FMIC while your at it.

Actually, blower over driving on a stock car much over 5% even on the old blowers is asking for trouble.

I've got an early blower with 10% OD pulley on the 35th with no issues. Its got midlengths, big dog exhaust but stock engine rebuilt. The blower was in good shape, but i've seen no issues going 10%.

Now on my 89 I have the late 94-95 blower, rebuilt lower end, mid length headers with free flowing exhaust few mods here and there and I went with the ESM 10 rib kit which is about 12% OD and i blew the gaskets. COuld it be that 10% OD is just too much for the late blowers?
 
my uncles 95 sc auto with manifold back exhaust,ported exhaust manifolds,double i/c with fan,upgraded fuel system,upgraded intake components wouldnt accept more than a stock 89-93 pulley.5% pulley dropped rwhp by 20,same dyno,same day.stock cam is likely cause.

I bet RWT went up like a sonuvagun though.

In addition to what DD said, using a lot of OD on a stock blower will create a ton of additional heat. That's sucking a lot of the power out of the additional air you're forcing into the motor. You're also getting additional pumping losses by spinning the blower faster.

Super simplified - too much OD = more pumping losses = more backpressure = more heat = more cylinder pressure = detonation = HG going byebye.
 
I've got an early blower with 10% OD pulley on the 35th with no issues. Its got midlengths, big dog exhaust but stock engine rebuilt. The blower was in good shape, but i've seen no issues going 10%.

Now on my 89 I have the late 94-95 blower, rebuilt lower end, mid length headers with free flowing exhaust few mods here and there and I went with the ESM 10 rib kit which is about 12% OD and i blew the gaskets. COuld it be that 10% OD is just too much for the late blowers?

It's all about the combination. I can't explain all the ins and outs of the different combinations but there are ways of using a late model blower with as much as 20% OD or more and not having problems.
 
alot of
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but generally speaking, the 94-95 blowers being overdriven 10%+ are riskier than an early blower on a stock-ish application correct? I'm trying to figure out if this was the cause of my blown gaskets...reason being....i want to see if I keep using the esm 10 rib kit on the 94 blower once my headgaskets are repaired or if I want to return to a stock pulley (or slap an early model blower and still use the ESM kit:confused:).
 
It's all about the combination. I can't explain all the ins and outs of the different combinations but there are ways of using a late model blower with as much as 20% OD or more and not having problems.

Jeez, I hope my combination is one of them. I will be running a late model blower on my early SC witha SCI 5% jackshaft and a SCI 10% blower pully.:eek:
 
A little off topic but part of the equation as a whole.

I alway assumed the later model exhaust was less restrictive just by the looks of it.

Has anyone actually done any testing similiar to Charles Warner on each exhaust setup?

http://www.sccoa.com/articles/cwexhaust.php

It's one of the best types of testing from a backpressure point I've read here.

Also I do recall reading that one of the main advantages of the late rmodel m90 is that it produces less heat for the same amount of boost. Something about more boost for same amount of blower rpm. Its more efficient.

I have to completely agree about OD' a stock 94/95 SC to much. My experience is that it will run like a bat out of hell untill the EEC says me no likey. My 94 with an ESM DIII m90 made 21psi (of boost and backpressure) with every bolt on known to man. Ran great down low...Had some sort of turn me off switch up top. And Fords safety measures must have been on top as I never blew a gasket.

But as Dave said its the whole combo. (which is something that can be debated and discussed to death)
 
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