3.6 liter High Feature I a Fiero (Page 7/15)
dobey SEP 18, 03:56 PM

quote
Originally posted by Crytes:

So how high does compression get before an engine stops being spark ignition? Or is the practical limit on compression from some element now? What I want is a street friendly 500 hp fiero with a power tain about the same weight as stock and decent milage for commute driving. I'm thinking this will require leveraging and pushing all the technology available to it's practical limit. Or just a pipe dream.



Compression ration is unrelated to whether an engine is spark ignition or not. An engine not being spark ignition means it doesn't have spark plugs applying spark to the compressed mixture for ignition.

As far as getting 500 HP in a Fiero with decent MPG, well, like fieroguru said, are you talking BHP or WHP? What is "decent" MPG for you? Being able to make a 500 HP number on a dyno at peak, and getting decent MPG are two very different things. It's possible to do both, but it requires an engine built to do that, and a decent understanding of how to get it. The easiest way to get both optimal HP and optimal MPG, is to go with as small an engine as you can, which can handle as much boost as possible, with a turbo. With the right combination and boost control, you can totally disable boost at cruise speeds to get maximum MPG, or turn it all the way up when on the dyno, to get maximum HP. Anything over about 250-300 HP, you will never actually put to the ground during a normal commute in a car that weighs as little as the Fiero does.
dobey SEP 18, 04:01 PM

quote
Originally posted by bmwguru:

One issue with the stock ecu was the vehicle speed sensor. There is not a sensor in the transmission on the Saab F40. It uses the ABS module to send the VSS signal on the can bus line. I wasn't about to add that in. The AEM wants to know the VSS also, but I spoke with Speedhut (the manufacturer of my gauges) and they do offer a VSS output from their GPS speedometer on some models.
I'll have to update my build thread one of these days....There is quite a bit to update.
Dave




Really? I thought it had a magnetic sensor above the ring gear? The F40 MT2 trans in the G6 certainly does have a VSS.
Crytes SEP 18, 04:59 PM
There are many ways around a VSS. GPS devices are simple to install but have accuracy issues. You could make your own as well. If I remember right you are just looking for pulse at a rate of about 2000 per mile depending on your setup you could arrange one or hall effect sensors on your drive shaft these can be designed to give a direct signal or to be modulated to calibrate for different size tries. And with a sensor one each side of a drive shaft you can measure flex which after calculations can be used to give you real time torque/hp measurements.
gtjoe SEP 18, 06:55 PM
I wonder if it would be possible to put the vss from a g6 f40 in the saab f40?
dobey SEP 18, 10:50 PM

quote
Originally posted by dobey:


Really? I thought it had a magnetic sensor above the ring gear? The F40 MT2 trans in the G6 certainly does have a VSS.



Oh, I guess the Saab and Ecotec versions of the F40 don't have a VSS: http://zzperformance.com/ecotec/f40-base-kit.html

But it looks like their half shaft and sensor bracket could be used, to add the missing VSS. It might be cheaper to just get a G6 trans, split the case, and use the High Feature bell housing with the G6 guts half, than buy that ZZP kit, though.
dobey SEP 18, 10:53 PM

quote
Originally posted by gtjoe:

I wonder if it would be possible to put the vss from a g6 f40 in the saab f40?



It appears not. It's possible the case could be machined to accept one in the same location though, but not sure if anyone's ever done it, what the cost would be, or if the ring gear in the Saab/Ecotec versions of the trans will work with the VSS.

Edit: Found some much better pictures of an Ecotec version of the trans, and it looks like the rear half casting is a fair bit different, and it cannot be machined to fit the G6 VSS at all.

[This message has been edited by dobey (edited 09-18-2016).]

Crytes SEP 19, 04:12 AM
The different F40s look to be totally different castings so my guess is while generally anything can be made to fit I doubt it will be plug and play on a transmission for an application that didn't need it.
mender SEP 19, 10:54 AM
People seem to forget the Jag HE engines with up to 12.5:1 compression:
"A high-efficiency 5.3 HE version debuted in 1981. This used the special high-swirl design "May" cylinder heads, and had an unusually high compression ratio (10.5:1 – 12.5:1, depending on market and year). In any given market, power levels remained similar to the previous model, but fuel economy was improved by nearly 50%. The HE V12 engines had a fuel injection system from Lucas (dubbed Lucas Digital P) which was based on the Bosch D-Jetronic system.[7]"

For VSS, one can use a wheel speed sensor directly; that might be easier than retrofitting an F40 trans. Hopefully I will have time soon to finish the F23 to HF brackets and get my 3.6 swap going, pretty sure the F23 has a VSS.

[This message has been edited by mender (edited 09-19-2016).]

2.5 SEP 19, 11:14 AM
Is there a reason its called "High Feature"?

[This message has been edited by 2.5 (edited 09-19-2016).]

ericjon262 SEP 19, 01:03 PM

quote
Originally posted by mender:

For VSS, one can use a wheel speed sensor directly; that might be easier than retrofitting an F40 trans. Hopefully I will have time soon to finish the F23 to HF brackets and get my 3.6 swap going, pretty sure the F23 has a VSS.




it does, or at least the metric bellhousing version does.