A couple questions about pistons and turbos

[turboshad]

First question. I am getting ready to order my pistons for my 2.4 swap. I will be going with wiseco b/c I have had them before and they have proved themselves to me. My concern is their 2.4 pistons yield an 8.8:1 CR. I like the idea of a higher CR but I also want to make my way towards 500whp and don't want to build the engine again. I will be going MSnS so I will have full control over spark and fuel. With this control should I be able to tune out the inherant detonation problems or should I get a custom lower comp piston made? I don't really want to go as low as 8:1 if I don't have to but maybe something in the middle like 8.2 or 8.5.

The next question pertains to the turbo. I was originally thinking a 50trim T3?TO4E with a stage III and .63 housing. From looking at the maps and other peoples experience it looks like this turbo would give out in the mid 400s and I would eventually need to upgrade to reach my 500 goal. That is OK with me b/c I can afford a GT30R right now which is what I would eventually like to have. I was also thinking of just using a Holset HY35 or HX35 so I was wonering if anyone had a link to the compressor maps so I can compare my two options.

Any help on either of these questions would be awsome.

DJ

[speeduphoria]

on 8.8Cr your only going to get to ~16psi on 93 octane

[kedavis]

Quote:

Originally Posted by speeduphoria on 8.8Cr your only going to get to ~16psi on 93 octane

and thats with 13 deg.total advance,I run the smc methanol injection and I have ran as high as 23 psi on 93 with the same advance methanol is magic

[speeduphoria]

http://www.***************/turbocalc/index.php

the GT30R is barely larger than the 50 trim, but so is the HY holeset. They are all good turbos. A HX w/ a bullseye housing is a nice turbo as well(so I hear)

[turboshad]

I see a couple guys on the SRT forums running the Wisecos with high boost but I think the margain for error would alot smaller than a lower comp piston. From everything I have been reading the 16V should be able to handle a higher comp piston than the 8V so would a 8.5 still be too high or should I just be sticking to the 8:1. I will talk to Chris to see what a set of custom wisecos would run since I will be using the .927 pins anyway.

As for the turbos I was more concerned with my first build stage. The GT30 or 35 will come later once I progress a bit more and do more research. I was leaning towards the TO4E 50trim b/c I had one on my 8V and liked it. Thanks for the link to squirrel performace. HX map looks like it will be a little big for my first stage of the build. I would prefer to have a little more head work done before I go to something of that size. I think the only thing keeping me from the HY35 would be the dry center section and it doesn't look as nice as the polished Turbonetics unit from TU.

If I went with a 50 trim does anyone have experience with the stage V turbine? I was originally thinking of using a stage III but if I could still get full boost before 4000 with a stage V I wouldn't mind that.

On a different note how do you go about estimating your VE when trying to map the engine on a compressor map? When I throw in a goal of 450hp with a 2.4l and BSFC of .55 with the VEs that default with the squirell performace calculator I get pressure ratios around 3.7. Now I can adjust the RPM points, VEs and Temps to get what I want but this doesn't seem like the right way to do it. Is there a good way of estimating these numbers? This has always been my stumbling point when it comes to actually getting an engine curve on the compressor map.

DJ

[shadetreeshop]

The cool thing about MS2 is it has a AFR map, so it's not an issue to tune the upper portions of the map, but a Pressure ratio of 3.7 , i'd get the 4 bar map upgrade with the MS, I'm currently running my 2.5 w a 95 16v head and it's a breeze when you get to understand MS,


I'm sorry if i'm off topic here

[speeduphoria]

well according to Frank who wrote the calculator(w/ info from Garret) the BSFC is more like .47 for the 2.4 and if it is highly modified/efficient, more like .43

Also there is nothing wrong w/ oil only turbo's especially w/ modern synthetic oil.

If you are using a engine managment sys, like you are planning, then 8.8CR is not a prob, you just have a lower pump gas boost.

A couple of hybrid guys say they woud have liked to run more like 9:1 CR, and many 2.4's run well w/ the weisco pistons.

Also for a little info I found, the JE 8.5CR pistons have small valve reliefs compared to the Weisco's and a couple of unknowing SRT folk have had piston to valve contact w/ these and oversize valves or Crane 16 cams or larger, just an FYI(you can send them to DCR and they will cut the reliefs bigger for $100)

[turboshad]

Quote:

well according to Frank who wrote the calculator(w/ info from Garret) the BSFC is more like .47 for the 2.4 and if it is highly modified/efficient, more like .43

That's good information to know.

Quote:

Also there is nothing wrong w/ oil only turbo's especially w/ modern synthetic oil.

That's sort of what I was thinkng after starting this post too. Plus I always use a turbo timer and heck diesels have been using the Holsets with dry center sections for years with most guys not even thinking about letting them cool down (albeit diesels do run alot cooler in the exhaust department) I finally found some rough HY35 maps and they looked pretty good to me. That coupled with some stories of others who are using them I thought I would look around for one. I found an HE351 on ebay and the only difference I found might be a larger comp wheel than the HY35. I bought that item and I figured if it turns out to be too laggy or if it is surging then I will swap with my cousin who has an HY35 on his cummins.

Quote:

If you are using a engine managment sys, like you are planning, then 8.8CR is not a prob, you just have a lower pump gas boost.

Well that was sort of my thinking. I would be more weary about it if I didn't have full fuel and spark control. I think that is the route I will go and I will see if I can get some made with .927 pins since that is what my rods are bored for.

Quote:

but a Pressure ratio of 3.7 , i'd get the 4 bar map upgrade with the MS

The 3.7 was just what the calculator gave me. I really don't want to run this high if I don't have to. I will be getting the 4bar MAP though b/c I hate buying stuff twice just in case I might want it some day. I'm hoping the decreased resolution won't be a problem.

Thanks for all your input. I am excited to get this running by spring. Hopefully that's not too much of a dream. I will keep you all updated.

DJ