V8 Conversion to a NON "S" Boxster

[Wendo]

Hello, new guy here and the title sums it.

I like the five speed and have a way to possibly keep it with converting. First, nice little car with a non running 2.5. Most of my research proves against a non "S" conversion for two reasons.

1) The low gearing would drive me nuts with engine RPM, and more importantly engine heating. I was looking at a taller final drive possibly, I think one taller is available.

2) The strength of the stock gears. I was looking into cryo hardening the gears and ring and pinion.

I am not the type of driver to hurt a car but it could hurt itself. I would lift to 350 to 400 HP and about 350 t. I think I have found the right place for the best feedback. And its OK to accuse me of ruining a perfect car, been there. Thanks everyone and drive safe.

[Pdwight]

BoxsterLS376 introduction - LS3 conversion :)

[PaulE]

Originally Posted by Pdwight

BoxsterLS376 introduction - LS3 conversion :)

Thanks for that! I just used up my morning!

[Wendo]

Thanks Mr Pd, I did learn some stuff in that. However, I am definitely along that path but different. He was starting with the correct car, and was intending to spend money, I think he would have success and fun but my story is different. I am thinking of making use of a car I have. It is known that the "S" has much more to offer the concept, starting with a 6 speed tranny giving a taller final gear. Along with suspension, bigger brake discs and other things. Grown up in Detroit, mindset that cars are made every day, just can't dump into them capital conscious free. I am up on all the conversions offered and know just what is needed and what is not. I am not fond of the 6 speed gear pattern, I like the 5 because its more effective for sport. Both cars may never use 1st just for thought. My interest here is to gather any information or negative experiences about the 5 speed tranny that anyone could share, if anyone has comments. But, Mr Pd, that was very cool, thank you I intend to keep that as a valuable addition to my planning. Thank you and drive safe.

[78F350]

I'm not sure if I saw any direct questions there...

What I have read and heard:
-3.4L 996 engine swaps have been done plenty of times with the original 5 speed transmission.
-The 987 5-speed transmission is more robust
-The VAG O1E (6-speed) and O1A (5-speed) transmissions have the same basic bolt pattern as the 2.5L Boxsters. There are lots of variants. You can look at Audi and VW Passat forums (VWVortex, Audizine, ...) for ratios and thoughts on those. -Generally they say if you hammer the gears of the 5-speed with a huge Tq spike, it will shed teeth.

[Wendo]

Thank you Mr 78F350, you did catch my question because you answered it perfectly. I was just generating food for discussion on the 5 speeds and you helped. The gear tooth strength was the concern that directed me to Cryo hardening. Cryo can more than double the gear hardness and toughness. We have done ring and pinion assy's for years in off road Baha Competition. This is an incredible and fast growing concept for drive line weak links. Thats fantastic to hear, thank you.
I have looked into the 3.4L swap but Porsche engines are one of the most precise and intricate machines made and to score a good motor you pay dearly, I could end up with 25k into a 10k car. And miss out on all the bandaid use. Thanks again Mr 350, yes great truck.

[ltusler]

"I could end up with 25k into a 10k car."

And you won't doing a LS conversion?

[Pdwight]

But first what I know about the LS conversion I learned from the thread I posted...no actual empirical experience. I remember when I first got my Boxster and the horror stories about IMS bearings turning fine German engines into scrap metal in the blink of an eye...how if you said IMS three times into a mirror at Midnight your car would never run again.....( well I made that one up). But seriously what I remember was the continual barriers he ran into all the while the Renegade commercials made it look like bolting in a new water pump...Our board member shared all the intimate details with us over his ordeal and how much Renegade left out or just id not know and how utterly incomplete the kits really are. While the thread was about a different swap there was still mountains of information to be gleaned, red flags so you could avoid land mines if you chose to go that way. So if I was a little terse I offer a Gentleman's hand and will say I was only looking out for you so you could research , research , research and make a better call for you project.

If you decide to proceed with you project we will all watch closely and wish you the best and any advise we might be able to give.

All my Best
Dwight

[Wendo]

Thank you both Mr Itusler and Mr Pdwight again. I am not one for making Boxster lovers fear. To me the IMS Bearing is a lot like politics when sorting truths, he said she said. But airing on the side of caution, no large capital is going to a flat six here. But, a good looking car should be a running car, and it should run like it looks. My thoughts on conversions are 1) A person should understand the logic in the plan, in the end, you have a car. 2) A person should listen to all that is kindly offered by the experienced. 3) A person should only venture within their own skill level. 4) Beware of snap together kit sales, most can be designed and implemented by a decent inclined mechanic that also listens.
To begin, just transition bell, flywheel, p plate and clutches are more wisely purchased than self machined. The rest isn't much more than competition rail frame building, trial and error.
Cooling and wiring are the fun part, after it can be seen together.
I have been to this rodeo, trust me, its not that far above most mechanics, if any at all.
The hardest part is not butchering the car, measure, draw and model if needed to see fits and hidden speed bumps. A very nice concept can be created at home with the care and safety always in mind.
This is great, thank you all and keep driving safe.

[Wendo]

This is my first porsche and so many designs in this car are seeming totally negative.
It is a 1997 Boxster 2.5l and I just can't believe the electronic nightmare waiting to speak to me.
They are beautiful and sexy, some say a total joy to drive.
I am happy owning it purely for the uniqueness.
But I am looking at a total engine and wiring changeout.
I am loosing the immobilizer first, that sucks, total rewire for that alone.
Yes, including window action from door handle. (plc)
It was headed to the garage for an engine conversion last week.
Now it is going to the SHOP for a total re-gutting.
I love the car, and all the people that are Porsche lovers.
But I just can't live with all the uncertainties.
How do you do it?
I am going to try to make this thing livable.
And powerful.

[rusty69911]

Wendo,
I am swapping an audi v8 in mine, its well covered with a search and seems the simple option, my car is a $1000 wreck so I dont have much in it and even less to lose, I sold my old motor for parts which brought my flywheel and clutch, I bought a whole running A6 v8 for $900 (about $750 US)
the hard bit would be removing the imob module as it works so many things, luckily mine is ok, I hope...
as you say it is a pretty straigh forward swap it just people bite off more than they can chew,
modify as little as possible to achieve the goal,
clearly set your goals first up,
Cheers Russ...

[Wendo]

Hello Rusty
I also like the audi v8 idea.
Mainly because I have heard they bolt right up, if that is true you may gain very valuable front of engine room not adding an adapter plate.
Outside of that I can only say they do sound good.

The immobilizer has inputs and outputs like any other computer component, can be researched, understood and manipulated.
My point of interest begins more in what actually happens in the DME or ECM. The power source gets cut off by the immobilizer and that has to be via relay or silicone component, both will have metalic leads, metallic leads that are screaming for a soldered on jumper wire. SHAZAM!! engine never gets effected.
But for that matter, your Audi and my LS will both have new sensors and controllers.

Back to the many gremlins inside the immobilizer,
I think mine is ok also, but I will sleep better without it.
Again IO logic.
Its either TTL or Cmos, the only real difference is operating voltage.
I expect a lot of "if this, than that" simple logic inside. Once I enter that stage I will without any doubt master it and retain it. It will be my lifes ambition.
My goal would be to replicate it with a more user friendly and maintainable unit.
Maybe an Allen Bradley programmable controller or a simple raspberry pie PLC.
Sounds like a lot, your computer repairman wants you to think that.
Good luck and also super job you are doing on the cost Rusty.
It will be an even more massive accomplishment if you never have to feel guilty about the money.

[78F350]

Have you come across this car yet in your searches?


All new aftermarket ECU and harness setup using an LS1 throttle body on an Audi V8.
One of his for sale threads:
https://rennlist.com/forums/vehicle-marketplace/952320-boxster-s-race-car-with-audi-4-2-v8-engine-and-lots-of-motec.html

Thread here starting with a Suburu conversion, then ABZ V8. Most of the pics are gone in the Photobucket:
http://986forum.com/forums/boxster-general-discussions/25697-boxster-subaru-conversion-interest-13.htm

Much of what you are looking to do, but $10s of thousands invested. Sure that much of it can be done, scaled back, for a lot less. Sad there weren't more done like this one, no doubt that this one was sold at a loss considering the craftsmanship and hours put into it.

AND, don't forget about Vlad. I don't think he completed his swap, but lots of great info:
V8 Conversion
Rolling Shell - Follow My Porsche Boxster V8 Build

As far as S vs Base, from the transmission forward, I really don't see any difference in the mechanics of the swap.

[rusty69911]

Originally Posted by Wendo

Hello Rusty
I also like the audi v8 idea.
Mainly because I have heard they bolt right up, if that is true you may gain very valuable front of engine room not adding an adapter plate.
Outside of that I can only say they do sound good.

The immobilizer has inputs and outputs like any other computer component, can be researched, understood and manipulated.
My point of interest begins more in what actually happens in the DME or ECM. The power source gets cut off by the immobilizer and that has to be via relay or silicone component, both will have metalic leads, metallic leads that are screaming for a soldered on jumper wire. SHAZAM!! engine never gets effected.
But for that matter, your Audi and my LS will both have new sensors and controllers.

Back to the many gremlins inside the immobilizer,
I think mine is ok also, but I will sleep better without it.
Again IO logic.
Its either TTL or Cmos, the only real difference is operating voltage.
I expect a lot of "if this, than that" simple logic inside. Once I enter that stage I will without any doubt master it and retain it. It will be my lifes ambition.
My goal would be to replicate it with a more user friendly and maintainable unit.
Maybe an Allen Bradley programmable controller or a simple raspberry pie PLC.
Sounds like a lot, your computer repairman wants you to think that.
Good luck and also super job you are doing on the cost Rusty.
It will be an even more massive accomplishment if you never have to feel guilty about the money.

I think the issue is the immobilizer is also the body control module, the start part is easy to bypass if your doing an engine swap but the issue is the signal it generated to the ECU to allow start for a standard motor is hard to replicate, its not an on/off input/output arrangement, if it was it would be pointless having it as an immobilizer as it would be too easy to be overridden, the windows can be hard wired or done with relays, although the pull the door handle and the window drops a bit function will need some thought, the central locking can be bypassed, Ive seen a writeup on the net somewhere

[Wendo]

WOW! 78F350, Thanks again for you input, fantastic info, beautiful project.
Years ago a lot of us realized our pipe dreams really only had value to ourselves when talking money, ending in probably giving them away when we had to.
I am in the crowd knowing the project could and probably will end up taking up needed room, leading to that giveaway syndrome someday.
But without to much heavy investment, I am looking forward to the brainwork and fun of doing it.
Some love putting thousands in fishing.
Some are bourn for track like this fellow.
Some are happy spending a third of there life on the stool at the pub.
We live once, do what feels good.
Its, as we all know, not the return from a sale, count that out right now.
But it does help some to keep cost down.

As I continue to learn, this just keeps getting better.
Now the Audi and body control.
This is how things get done.

My thoughts on the immobilizer.
1)Up stop for window-current relay-delatches on high current-never have to program windows after battery is removed. Kind of the same little goody that throws your refrigerator motor from start winding to run winding.
2)Down on handle motion, again latching relay with resistor bleed down, and to add-a trimmer pot to set the distance.

Just two minute thoughts, man made it, man can change it.

As far as the immobilizers security, I have read they are not that good anyhow and have been hacked many times.

I am still searching for all that is related to the unit.
One thing that is bad, running the battery down to far can damage the immobilizer.
A super big reason to loose that guy.

I am very happy with this site, many have worked hard to make it, and its proven by the quality of people and knowledge offered. It takes time from all of us to participate.
I will be looking at ways to post photo's of past projects and present.
Thank you all, drive safe.

[rusty69911]

yes you could use a current sensing relay although the ones in a fridge motor are AC and are non adjustable,
this would work,
AIROTRONICS HCSDC045A Relay,Current Sensing,45 Amps | eBay
although I dont really see a need for it, I would just wire a DPDT momnentary switch in there,
and yes the immobilizer can be programmed out so you no longer have to worry about it but depends on how much $$ you want to spend,
as for the window drop on door open, that will require a bit more thought, you would have to use a capacitor resistor combination to give a time deay or use a timer circuit using a 555 IC driving a transistor output to a relay,simple just needs some thought

[Wendo]

Cool Rusty, you are on it!
I am going to guess you know about the raspberry pie PLC.
If we can talk on that level no need for layman examples and we will build this.
The pie has all the inputs and outputs, I think if I remember it has about a dozen lm 555 timers, drivers for seven segment, crystal sockets and current abilities, all about the same size as a pack of smokes. 25.00 USD.

We do need a drop on door handle action for a soft top, hardware is already in the door.
Stay with me Rusty.

What other features are locked in this immobilizer that will need to be addressed?

[rusty69911]

yeah arduino is the way to go, they have analogue inputs too so you could use current sensing if you really wanted to keep the auto up/down,
central locking can just use an aftermarket fob and controller and wire to existing locks

[Wendo]

Rusty, I would like to know your reasons for Audi.
I have heard some but not much.
I have not bought into the power plant at this time, I would like to know about all the options.
I am not racing, just would like 3 to 350 hp.
And I am sure you must save front engine space.
What is standing out to you with Audi my friend?

[rusty69911]

well the main reason cost,
1: whole donor car less than a grand,
2: no added cost for adaption, $570 for a v6 turbo flywheel and clutch, all bolts up
3: no chopping of front xmember to fit, no need to alter waterpump etc
4: simple to adapt ECU (although this is the same for an LS )
5: 300hp stock so easier on the trans but enough to make the car a bit quicker

my motor had sustained water into #1 cylinder (rain entering via manifold burn hole) so potential $$ to repair and also fire damage to top of motor so lots of small expensive plastic parts there to replace, sold old motor for $500 so that offsets motor cost,
my donor Audi is the 01 model and seems to be the best of that series of motors for reliability