Phyxius Posted March 21, 2005 Share Posted March 21, 2005 I was wondering if any of you who have installed intercoolers have noticed an increase in turbo lag as the piping size increases, and how bad the lag increased. I'm specifically interested in 2.5" and 3". Quote Link to comment Share on other sites More sharing options...
mtcookson Posted March 22, 2005 Share Posted March 22, 2005 lag will increase with the more space that it has to fill (i.e. if there's more area for there to be air in the piping, it'll take slightly longer for the turbo to fill the pipe up compared to that of a smaller pipe). at a certain point you'd have to go up to a 3 inch setup once you're pushing enough power, but i'm not really sure what the limit is. what kind of power are you looking at getting? Quote Link to comment Share on other sites More sharing options...
Phyxius Posted March 22, 2005 Author Share Posted March 22, 2005 My goal in the end is 450hp. Right now, I'm a shade over 200. I've got a nice aftermarket turbo and I'm megasquirted. I've got new injectors and this new intercooler to install. I'm hoping with these 2 mods i can get up to 300. Quote Link to comment Share on other sites More sharing options...
GrayZee Posted March 22, 2005 Share Posted March 22, 2005 My goal in the end is 450hp. I'm sure you don't need 3" intercooler pipes to achieve 450HP Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted March 22, 2005 Share Posted March 22, 2005 3" is pretty big... not sure if that's maybe TOO big even for 400+hp... I'd think 2.5" should be enough? I'd think the lag increase would be very noticeable from one size to the next. One important factor is the size of the inlets on the intercooler itself? My I/C has 2.5" inlets, and I'm using 2.25" piping... I was actually able to fit the 2.25" silicone couplers over the 2.5" inlets, pain in the *** but doable, but if you're going more than .25" change you're gonna be spending more on the step up couplers. If possible either way you're better off going with whatever size the inlets are on the I/C, IMO. Quote Link to comment Share on other sites More sharing options...
Phyxius Posted March 22, 2005 Author Share Posted March 22, 2005 inlets on the IC are 3" It is a monster. The store I bought my turbo from recommended 3" pipes for 400+ hp. Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 22, 2005 Share Posted March 22, 2005 You won't notice the difference from the extra volume. I went from 2" pipe to 2.5 in / 2.75 out and a much larger intercooler. I wouldn't go larger than 2.5 into the cooler. I ran 2.5 in becuase that's what the turbo outlet is. I ran 2.75 out because that's what my TB was. My intercooler also has 3" in/out's, 4" thick core. Is your 450 hp goal crank or wheel? How much boost and what turbo? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted March 22, 2005 Share Posted March 22, 2005 You do not need 3" pipes for your HP level. Pretty sure your compressor outlet is 2", so you do not really need more than 2.25 to the I/C but using 2.5 makes an easier transition to 3". I am well over 500 at the wheels and transition my I/C inlet from 2" to 2.5, then blew out the end of the 2.5 to 3 to mate up with the I/C. From the I/C I reduce it to 2.5 to the TB. BTW, too much is being made of lag and "filling up the pipes". The main cause of lag is the wrong turbo components and running too rich in the low end. If you properly size the turbine wheel and housing and not have the engine load up on the bottom end, lag is not an issue. Need to remember that an L28ET is a low-compression engine with probably less torque than an N/A off boost. So, you are going from less torque than an N/A to probably 50% or more torque with boost and how well it transitions to full boost determines "lag". You need exhaust energy at low speeds to get that turbine wheel spinning up to 80-90,000RPMs and a bigger/heavier wheel and larger a/r housing needs even more exhaust energy. For a street car that wants snappy response, do not go crazy on turbine side. Quote Link to comment Share on other sites More sharing options...
Phyxius Posted March 22, 2005 Author Share Posted March 22, 2005 my problem with going 2.5" is that it is a lot cheaper to go 3". There are less couplers and such, and 3" pipe is less expensive on ebay than 2.5" Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted March 22, 2005 Share Posted March 22, 2005 Well, I am going with 2.5 inch and my IC has inch outlets and I got all the couplers I needed for $25 shipped. i think the the seller ID was fcdtuning Quote Link to comment Share on other sites More sharing options...
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