rebuild 2.5 or build 2.8 then turbo....have ?'s

[DrMcDave]

alright i am about to start gathering parts for an engine rebuild. I was considering sticking with a 2.5 and saving some money since i will be putting a turbo on at some point. However i am wondering if you all think it would be worthwhile to go ahead and build the 2.8 then turbo that. I already have a 524td manifold notched to fit my engine. although i am not nearly ready to take on a turbo project, i picked it up off ebay. what i really need to know is what compression pistons should i go with. I don't plan on going real high boost because the ix driveline just won't have it....i was thinking like 10 psi max. so share your thoughts

a) rebuild 2.5 then turbo
b) rebuild 2.8 then turbo

why, why not and what piston compression....car will not have turbo for a while after engine rebuild due to $$$

[Diplomat]

im not a turbo expert but i guess i could help..but what kind of turbo is it?

[UNHCLL]

Re: rebuild 2.5 or build 2.8 then turbo....have ?'s

alright i am about to start gathering parts for an engine rebuild. I was considering sticking with a 2.5 and saving some money since i will be putting a turbo on at some point. However i am wondering if you all think it would be worthwhile to go ahead and build the 2.8 then turbo that. I already have a 524td manifold notched to fit my engine. although i am not nearly ready to take on a turbo project, i picked it up off ebay. what i really need to know is what compression pistons should i go with. I don't plan on going real high boost because the ix driveline just won't have it....i was thinking like 10 psi max. so share your thoughts

a) rebuild 2.5 then turbo
b) rebuild 2.8 then turbo

why, why not and what piston compression....car will not have turbo for a while after engine rebuild due to $$$

This is essentially the same process Matt325is (I think thats his SN) did. He built a 2.8 and broke that in normal for a while, then went ahead and turbo'd it. He seems to be VERY pleased with his results.

[rward325]

My vote is do the 2.8 and then Turbo it like Matt did.

[diegom6]

what ever you do, you will get nearly the same outputs HPs, and the toruqe is the only thing that probably will be slighty different...290-300cc of difference, believeme , it's nothing in HP range, but something in toruqe yes....what turbo are you looking for or you didn't decide yet..?

[DrMcDave]

not sure what turbo...prob garret t3

but do you think its worth it to spend the extra money to do the 2.8 or just do the 2.5 and get the turbo on there sooner....cuase obviously the 2.5 will cost less....and i still need to know what piston compression to order.

[matt325is]

This was exactly what I was going through 1 year ago. I was seriously debating to turbo a 2.5/7 or go bigger 2.8, or just N/A 2.9 or 3.0. I obviosly chose 2.8l turbo. One of the major things that set me that way was how rare a 2.8l turbo e30 is. The only one I know of is me. Everybody else does 2.5, 2.7, or 3.0. Anyway, if you go with the 2.8, you will want something bigger than a t3, get at least a t3/t4, with a .60 or bigger exhaust a/r. I have a straight up t04b with an exhaust a/r of .60, and intake of .50. This turbo is really good for my application, and I will tell you how it responds when I get to higher boost. It all depends on how much money you have, how much labor you want to do yourself, and how fast you want to get it done. I started the project off by buying an IHI RHB6 turbo 1 year ago. I am now selling that turbo, too big for e30's.

anyway, good luck to you and your decision, if you have any specific question, please ask.

matt

[decay]

what ever you do, you will get nearly the same outputs HPs, and the toruqe is the only thing that probably will be slighty different...290-300cc of difference, believeme , it's nothing in HP range, but something in toruqe yes....

you are way off. displacement makes a difference all the way across the board on a turbo motor, as long as the head and turbo can flow for it. case in point, overlaid dynos of 1.6 and 1.8 turbo miatas w/ the same kit-

http://www.flyinmiata.com/tech/dyno_runs/1.6_vs_1.8_FMII.pdf

doesn't look like "just torque" to me.

drmcdave: i don't plan on changing compression ratio for 10psi. if you get a T3, make sure the turbine A/R is at least a .60; a .48 would choke way before it saw that amount of boost on a baby six (IMO).

[SickE30]

HaHaHaHaHa wtf? 2.5 and 2.8 make close to equal HP and a little bit more torque. Sorry bro. try driving a stroked M20 it is almost as good as sex.

[Werksmini]

I think he was talking about the 2.8 vs a Turbo. Not the 2 combined.

[SickE30]

All the same man. Unless that turbo kicks in at a hint above idle that .3 stroke is HIGHLY noticeable. PERIOD.

[MattE30]

I remember someone saying that you could use 325e parts for a 2.8 stroker. Can someone explain this in more detail b/c I have forgotten.

[SickE30]

Pretty much your eta block. Check out Fred's website.http://www.strictlyeta.net/index.html

[DrMcDave]

first off its a 2.5 turbo vs a 2.8 turbo...but i decided to go 2.8 turbo because i think i just found a td crank :)