TurboTim

They also had a dual port WG,stage 2 intercooler,injectors,MAP system and every thing else you can bolt-on.

TurboTim

[QUOTE=azmi951]I was wondering the same thing and just aquired a stock downpipe to use to make a 3" pipe. I will make a bracket that holds both of the flanges then cut the pipe section out. I will then make a new pipe section that tapers from the near 2.5 tubine outlet to a 3 inch.


Only problem with this is that there is such a tight radius bend here, where are you going to put the transition? Another thing you will have to do is put a small indent in the exhaust pipe for one of the factory studs so you can get a bolt on it.There there is the problem of welding a high nickel content flange with a MIG welder.Make sure you backpurge it.There was alot of thought that went into our pipe and granted the raw materials alone will only cost you about $100. The time it takes to make those flanges with crushrings has to be factored in along with building a special tool to indent the pipe for clearance issues.Then there is the TIG welding and associated costs of that.Dont forget labor and overhead,etc.........so that is why we set the rpice at $399.Now if we were to sell a gazillion of these we could drop the cost significantly.On top of that the parts we build are a track worthy product and we have some of these headers,downpipes,etc.... with over 10,000 miles on them with no issues whatsover.If you put something together and it fails, you need to take it back off and you guys know how much of a bitch yanking the turbo can be.So these are a few to things to consider.Take care.

fast951

I have seen SFR 3" downpipe, it is of a very nice quality.. More than likely, I'll get one myself for my own race car (when it's time to remove the turbo).. The time it takes to make one from scratch is much more costly than the $399..

89951DREAMER

I have been thinking about this post ever since I started it. I think that the most important aspect of the downpipe is that there is a smooth transition from the turbine outlet to the rest of the exhaust. I mean that if the turbine outlet is only 2", then a 3" down pipe would be a poor transition. I think that the pipe should match the turbine outlet size, and then gradually step up to the size of the rest of the exhaust system. This being said, I think I will stick with the stock down pipe since I have a stock turbine. It just seems to me that if there is a sharp step from the turbine to the pipe, this will create unwanted turbulance. In order for me to justify the extra $900 (the difference between the Lindsey and SFR systems), I will need to have a much larger turbo. Please someone correct me if I'm wrong.

Ian

Laust Pedersen

89951DREAMER, I happen to agree and think the effect of exhaust optimization is best put in perspective by considering the fact that the turbo has a max inlet pressure of at least 50psi. My guess for the outlet (static) pressure increase using an optimized exhaust system (relative to an OEM system) would be in the 3-10 psi range and since it is the pressure difference across the turbine that creates the turbo rpm and torque (boost) the relative boost gain is quite small. Similarly the evacuation of the cylinders.

Laust

bdellis

I had an extra complete cat. The original one was bad and when I bought the car it came with a new one. I made sure the seller gave me the old cat so I could make a straight pipe out of it. I welded two sections in and I noticed a pretty good difference in power. mainly it boosted sooner. I am sure the SFR unit is nice, but I hardly think its worth the price.I had a k26/6 turbo in my car for a while and I noticed a huge difference in the time too full boost with the straight pipe. Now I have a k27/8 and it takes a good bit longer to boost, but its well worth the wait!

By the way it was not costly for me to make my own out of the old cat. I spent about 20 $ to do this.

Bengt Sweden

I never said that you shouldn't have a smooth transition from turbine to downpipe. This doesn't mean that the whole downpipe should be small diameter.

Bengt

Bengt Sweden

Well, in this case you loose both pressure and velocity from beginning to the end of the pipe due to heat loss. This means that it is a radically smaller volume flow (same mass flow of course) towards the end and you can do with a smaller pipe. Not that it hurts with a bigger one.
Bengt

J Chen

Hi Bengt,
Sorry that I misunderstood your statement.

azmi951

Have you guys seen the stoc parts bolted together when they are not on the car (I have a stock pipe and -6 housing)? There is a large step in it stock. The outlet from the turbo is about 2" and the pipe is 2.5". I had tread Corky Bells book Maximum Boost and seem to recall something about preventing reversion. I will study it tonight and get back on this.

Laust is right, the turbing extracts power from the exhaust by means of a pressure differental. The higher the pressure in and the lower the pressure out the more power you can extract. The stock pipe leaves a bit to be desired. Especial when we bolt on bigger turbos and modify other componets.

Dark Lightning

For what it's worth, Garrett GT30 turbine housings have a 2-5/8" ID outlet. Seeing as the ID of 3" pipe is 2-7/8", it's really not a big deal. On a stock turbo the step would be a bit more obvious but in either case some diligent (and relatively mild) porting would help.

dmoffitt

guys, i don't want to stand in the way of innovation or DIY handiness but just make sure you are making these for you and your friends, not as a knock-off of existing vendors. while it might be legal to make a similar-but-not-exact copy of, say, Tims, it's kinda tacky imo. no point in reinventing the wheel just to undersell someone.

Dark Lightning

We're not buying an SFR downpipe with the intention to duplicate it; we're talking about how to go about making our own based on a stock piece.

While I don't intend to start manufacturing these en mass, I should point out something. If one vendor was the only dealer for a $5000 951 intake manifold, would anyone complain if someone else made a different intake manifold for $1000 not based on the first vendor's? So long as it's not a direct copy, it's all about capitalism.

dmoffitt

i agree 100% john, i wasn't trying to say you were, but topics like this have gotten ugly before. there's nothing wrong w/ competition... but i've seen countless times where between SFR, Lindsey, Huntley, etc one person comes up w/ something cool and someone on the 'list decides they are 'overcharging' and tries to dupe it - remember that Tial adaptor mess??

azmi951

I simply get a great sense of accomplishment out of "engineering" a part that fits the intended requirements. I have not even seen SFR's pipe but IF my own trial pipe doesn't work they will be getting my money for one. I have no intention of selling even one, I will simply be at school with no access to my own shop so I was reaching out to any fellow rennlisters that have a shop and are intrested in trying this project.
I agree with you dmoffitt it would be very tackey to duplicate with only minor changes. And I also realize that if I concider my time I will probably spend more than if I just bought one.

I really hope this isnt too defensive or doesnt offend anyone.