Mods for a 951

[hazmat]

Hello:

I have a 1987 951 (non-S) that I want to do some mods to. Here's a few things I'm thinking of:

1) Different turbo
2) Performance exhaust
3) 17 or 18 inch wheels/tires
4) Slightly stiffer and lower suspension
5) Possibly putting a 3.0 crank in to raise size to 2.8 litres

Up until this point, my car is completely stock. It still handles like a dream but I would like more power for having fun on weekends. I'm not looking at creating a monster or killing the excellent reliability I've gotten out of it.

I have no experience with mods on any type of car and I would welcome input from people who have gone down this route and have first hand expeirence with installation and reliability afterwards.

As I've said, I'm not looking for a monster, as this is still my baby and will be used just on the street. I'd be happy with around 300 HP to the wheels.

All comments and suggestions will be welcome.

Thanks!

Brett
87 951
02 325xi

[myskyon]

951max chips, 3"exhaust, 3 bar FPR (fuel pressure regulator), boost controller, Venturi tube delete, oil catch can, hard pipes, and MAF with mafterbunner (get it new something like the LR stage 2). and you should be pretty happy. but one thing is to first make sure every thing else is in top shape before thinking about mods. I have been noticing more and more people just getting a car then wanting to mod right away. not a good idea.
also one of those while your in there you should have your injectors cleaned and flow matched. very worth it. there is a guy called witch hunter who is great. you may have to do some searching for him. i live locally to him so i don't have his info on hand. also plugs and wires.
man there is a lot of stuff to look at before and while moding. start out slow save your money and have a reserve after you buy your parts yet before you install them because i cant count how many times i have starting digging into my car just to take something apart and realize that it "looked good" but wasn't once taken apart.

[hazmat]

Myskyon:

Thanks for the suggestions. This isn't a new car to me. I've owened it now for 15+ years and I love the heck out of it. Rebuilt the engine and tranny just a few years ago to get another 10+ years from her.

I do understand the 'check basics first' and I will be doing that before any modding. The first thing I plan to do come spring is filters (all), oil, coolant, water pump, belts, rollers, plugs, and wires. While I'm doing all that, I will be checking all other hoses, wires, etc to make sure all are still in excellent shape.

My ideas for modding are more long term - over the year to 15 months say.

Brett
87 951
02 325xi

[idesign635]

300 kit
http://www.lindseyracing.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=951PACK300
340 kit
http://www.lindseyracing.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=951PACK340

[Porsche-O-Phile]

Check your fuel lines + fire extinguisher before anything.

[nize]

do a bit of searching, everything you're thinking of and have mentioned has already been done, discussed, analyzed, and beaten to death. here's another thread;
Question about Mods from new owner

[nize]

p.s. going to 17-18" wheels will actually decrease performance. you know that, right?

[nynor]

Originally Posted by nize

p.s. going to 17-18" wheels will actually decrease performance. you know that, right?

really? i have 17" carrera cup wheels. how so?

[olstyn]

Originally Posted by nynor

really? i have 17" carrera cup wheels. how so?

Higher amount of rotating mass (assuming same tire diameter, metal weighs more than rubber, so bigger wheels = more weight, unless of course, you go to those carbon fiber wheels, but they cost as much as a decent 951 anyway) makes it harder to accelerate and brake. If you're also increasing power at the same time, you probably won't notice the loss (and even if you don't add power, it might be one of those differences you could measure but not notice).

The gain from bigger wheels/tires is of course better cornering ability through higher grip, so it's a tradeoff; if you're modding your 951 to make tons more power, just make sure your suspension is upgraded to handle the higher strain the bigger wheels and tires (and more power) will put on things and you're probably good to go. If you're only buying bigger wheels/tires, just be aware that you might lose a few tenths off of your 0-60 time, and that they do put more strain on your suspension components, which will likely wear out more quickly as a result.

[nynor]

gotcha.

[nize]

Originally Posted by olstyn

The gain from bigger wheels/tires is of course better cornering ability through higher grip

this is only true if you go to wider tires to increase contact patch.

most people (actually, all people so far) that i have seen going to 17" wheels do not go to tires wider than the available 9" width on the factory 16" cup wheels.

it seems that more than 99% of the time, people running 17-18" wheels on the 951 are doing it for the bling, without understanding they're sacrificing performance.

[nynor]

i am using them because that is what i have!

i also bought some boxter wheels with snow tires on them. both sets have 255 rear tires and 205 (i think) fronts.

i am not sure what the width of the wheels are. like i said, the one set is factory carrera cups and the other are factory boxter wheels.

[2Tight]

I agree with most of the above but all larger wheels are not heavier than OE designs. There is also the option of buying quality lightweight forged wheels in a +1 size that are lighter, stronger, and allow more rubber without increasing unsprung weight too much if any. I have 17" 3-piece CCW's in 9" and 10" on one of mine. The difference in combined weight with tires between the heavy 16" OE Turbo PD's with 235 and 245 was less than 1.5 pounds a wheel. I find the advantage of larger tires 275-40 and 255-40 is well worth it especially at higher speeds. The performance at limit is far better than with the 16's w/ S0-3's and the ride/suspension response hasn't suffered at all. The only negative I've found is that turn-in is a bit slower and the tires do tend to tramline more on grooved highway pavement than before. Big heavy cast wheels will instantly kill the joy of driving these fine cars as any significant increase in unsprung weight will do.

[cb951]

Wheels --
Imo, as long as the wheels are not extra heavy weight cheapos, going to 17" will do a couple things:

1. Reduce sidewall flex of a higher aspect ratio tire on a 16", thereby improving overall handling (slightly), especially steering response and cornering ability. Of course, going +1 or +2 on the wheels provides smaller performance gains than improving the spring/strut/shock rates or beefing up the sway bars (all done with a single, unified outcome in mind). I would think that improved handling would provide performance gains (lap times as well as safety and predictability at higher speed) which would far outweigh any additional rotational/unsprung weight issues.

2. 17" or 18" wheels also allow larger brakes, such as big reds or blacks.


General mods --
1. Suspension first. Struts/shocks, springs, torsion bars (and/or coilovers), sway bars, bushings, control arms (if the car is lowered). All of these should work together to provide balanced handling (to your liking/driving style).

2. Cat bypass (possibly full exhaust), dual port wastegate, boost controller (preferably electronic), increased boost, chips programmed specifically for the specified set-up (which frequently require a 3.0 bar fuel pressure regulator). Then, some gauges to make sure all of the mods are working properly/safely (boost, wideband O2, fuel pressure -- to start).

3. Then maybe a MAF and piggyback, larger injectors, larger turbo. Chips and/or fuel controller should always be updated for the specific set-up. AFR throught the rpm/boost range is paramount.


This is all assuming it's still a street car with some track time.

[88BlueTSiQuest]

I want some new wheels, for that extra 'bling'