hey guys ok so my 2.8 went a couple months ago due to the water pump pinion bearing coming loose and frying the rings! Well now I have the motor broken down to the block and I'm going to take it to the shop to be bored and stroked.
The question I have is what is the number to have the motor stroked to?
I going to have it bored .40 over just need the stroke number. I know the 3.1 crank is already stroked but don't really have the time to go to the PAP to take apart a motor for a crank. I also know about the 3.4 boogie but not looking to get someone elses problem right now...just need to get the motor back up and running until I get the crate 3.4 next year(2015)

So far mods I have for the motor/car if you want to know are:

Pacesetter Headers
Magnaflow Muffler
Underdrive Crank Pulley
Jet Stage 2 chip
MSD 6A
MSD Wires
MSD coil
Hawks Ram air Ducts
UMI LCA's
Lakewood 50/50 rear shocks
Lakewood 70/30 Struts
Auburn LSD- 28 Spline
28 spline axles from 92 camaro
Richmond 3.73 Gears

I'm going to be throwing in Crane cam's 2030 camshaft and eventually a set of 1.6 stamped rockers along with internals for the 700r4

 

Why not stick with the stock 2.99" stroke of the 2.8, if you're not going to source another crank?

I wouldn't offset grind a 2.8 or 3.1/3.4 crank to increase stroke, the rod journals are already small enough and any offset grinding to increase stroke will weaken the crank.

With the overbore you will be at about 2.9L displacement as it is.

 

I'm asking about the stroke because I thought it would be possible to stroke it to the same stroke of the 3.1. Is that possible. because I am trying to get a decent amount of power out of it. I know I won't get much but something better then nothing.

 

You need to get a 3.1/3.4 crank to stroke the engine to a 3.31" stroke. There is no way to offset grind the 2.8 crank to get that kind of stroke and be strong, and without needing custom rods and/or bearings.

 

guess I don't have a choice but to get the crank because that's what I want. I'm going to call the pull shop next to PAP and see if they already have one if not then off to the PAP on a weekend to get it....smh. ok so another question when I get the crank is there any difference in the bearings compared to the 2.8 crank or are they all the same size? I'm asking just incase I need to let the shop know when I take the motor in to have the short block built. and what exactly would the displacement be with the .40 bore and the 3.1 crank. wouldn't it be like a 3.2L I don't know the cu in. do you or anybody have an idea on that? Oh and about what horsepower to expect. I'm learning as much as I can. So I'm sorry about all the questions

 

Why are you SYH? This is how things like this work. You want to play you have to pay... or build...

All 1985.5+ 2.8 and 3.1 use the same size main and rod bearings. The 3500 is when the bearing sizes changed.

Yes, the displacement would be about 3.2L

 

I don't know what syh mean...but thanks for the info. I have no problem paying it or pulling it out! I just need to know so that I didn't mess anything up! I really appreciate it none the less! so how much power do you think it will make just how it would sit

 

A brand new crank is like what 90 bucks. And be ready to go

A used crank will more then likely have to be cut and polished which is about 125 bucks

 

Project, could you give me some places that have the new crank. I'm sure if anyone would know it would be you!

 

one other thing Project, do I need to get bigger injectors like say from the 3.1 or the 3.4 or are the injectors from the 2.8 more than enough?

 

the stock injectors will support the lil bit of extra power u will get , call up ur local parts stores most of them can get a new or reman crankshaft cheap, if not they come up on ebay all the time cheap as hell

 

You will only get 160hp max out of the stock injectors before they go static. You can look at different size injectors but if go to big and dont tune the ecm you could be terribly rich and fowl plugs exspecially at idle

 

na they will do a bit more before going static , but hes basically building a stock 3.1 so it might make 140 hp insted of 120 that he had with the 2.8

 

@ 15lb injectors and 100%dc hes looking at 163Hp max. What are stock 2.8L stock injectors though?

 

at what bsfc ?

 

so I checked autozone and the crank is almost $200. so should I get the 3.1 injectors then and Fasteddi is the hp rating you gave with the cam and lifters. and what did guys mean by DC and BSFC?

 

what is the cast number that I need for the crankshaft and how do I know which one has the crank sensor provision or not or all they all the same/will work even if it comes out of a 3.4 with the crank sensor?

 

3.1 or 3.4 crank will work , fastedi is actually tearing down a 3.4 fwd engine maybe he can sell u the crank out of it cheap

dc = duty cycle , and bsfc is fuel consumption and n/a engine runs leaner then a forced induction engine so its needs less fuel under the same operating conditions

15# injectors on a normally aspirated engine will do 175 hp at 80% duty cycle on a turbo/supercharged engine they will only do about 150hp at 80% duty cycle


i just checked on ebay and theres no cheap cranks atm best deal was 160$ including rod and main bearings , call up a few other parts places sometime sprice will vary greatly between them

 

ok I see what you're saying and I checked ebay and found some for $80 and $95. think you could take a look at them to let me know if I can use them for my build? type in 1990 chevy 3.1 crankshaft and they'll come up if I can't use them then I'mma call this shop tomorrow in ontario call w&t auto parts to see if they have the crankshaft or if they can get it for me. they're usually pretty cheap when it comes to parts they'll even go pull a part for you from pick apart.

 

When using a bsfc of .45 i get 160hp at 80%dc. Belive me the stockers are junk when u push them and will go static closer to 85%

 

ok real quick question...can I use flat top pistons with this build or do they have to be dished?

 

being as ur building a 3.1 u have to use the correct dish pistons for a 3.1 , make sure u get pistons for the iron heads , if u get aluminum head pistons u will have something like 7.0-1 cr
if u were building a 3.4 u could use pistons for the dohc 3.4 which would bring cr to 10.2-1

 

for some reason i used .40 opps lol

 

so how do you know what .40 pistons are for the aluminum heads and the iron heads.. think you could give me a list of brands/part numbers for the iron head ones?

 

So is there any way to make sure I have the right pistons for the build?

 

you have to look at the CC of dish on the pistons. I cant tell you off hand what size they are but if no one replies ill post it after work as im getting deep dish ones for my hybrid build, i have the iron and aluminum ones wrote down.

 

Thanks for the reply Fasteddi. I appreciate that a lot. would you also have an Idea if you don't already know of what my compression ratio would be?

 

I went on summitracing.com and found the dished pistons....so I know the bore size is 3.543 for the .40 over pistons. I'm guessing the compression distance is the difference between the aluminum and the iron heads.... they have 2 different compression distances to choose from...1.450 and 1.442. I'm sure that's what Fasteddi is going to let me know when he chimes back in, which one to get. I also need to know the pin diameter...which is the right one also....0.905 or 0.906?
I know I'm asking a lot of question but this is going to be my first build and I want to do it right...And I just want to say thanks for the feedback on this because you guys are really helping and teaching me a lot

 

Yes 3.543 are the .040 pistons(90mm)

You going with a 2.8L block using a crank off a 3.1L or 3.4L right? So you want 2.8L/3.1L pistons .040 over iron head pistons?

This piston pin should be 0.906" for stock GM 60 degree V6 rods.

If your looking into the compression distance you want the 1.442" for a distance on the pistons for gen1 iron heads.

This is the pistons you want, if you go though summit for replacements for a .040 piston for a 2.8L/3.1L Iron headed engine:

http://www.summitracing.com/parts/sl...make/chevrolet

As for the compression ratio. It should be 8.6:1 or so but if you get different head gaskets (stock is 0.040" i think) or mil the head down it will go up a little.

 

Thanks a lot Fasteddi I can honestly say I would be lost without the help! So now that I've got piston specs all I need to do is order the crankshaft and cam, pull the motor and send it to the shop with the shopping list of parts they will need for the build!
Any Idea on the compression ratio would be yet? And I wanted to swap out my jet chip for a new chip...I was thinking about calling fast chip but is there anyplace or do you know of anyone who can burn me a really good one?

 

I have 2 extra crankshafts if you need one let me know. If you can get one under 100 bucks then you doing good because it would probly cost me 50-60 bucks just to ship it to ya it weighs so much...

Are you planning on getting a cam from delta cams or a different place? I really reccomend a delta 260 grind cam. Its a good mild cam and cost about 125 bucks shipped to your house with a matching lifter set.

Your compression ratio isnt going to really rise up. Think of your build as a 3.1L now. Thats all your doing to it else then the bore.

Ive never heard of fastchip. I burn my own and self tought myself how to a few years back with alot of help from members on here and a few other boards. You have a MAF ecm not speed density like I have, so im no help as my experience is almost specific to speed density 7730 ecms. But as my memory serves me right you MAF set up will make up for alot of the gains your doing to the car. So a tune isnt as crutial as it would be for a speed density car. If you start to do some serious mods though you'll need to get someone to tune it though, specifically if you put some big injectors on it.

 

No dice on getting one for under 100 out here, especially with the machining cost they charge out here. whether it's brand new or out the block with machining, it's going to cost 200! Don't know why it's so expensive to machine a used one but it is sadly! And If you were to send me one how would I send the money?

And ok I see what you mean about the compression and it being a 3.1L. Compressions either going to stay about the same or go down to 8.5.1...That's cool

And fastchip is a company that only does GM computer tuning. Their chips/tuning and programs blow out just about everyone else. They'll burn you chips until your tune is the way you want it! Lifetime warranty too which is really rare! I think some of the guys on here use them IIRC

 

Ill check to see what it would cost to ship a crank out to cali. Ill pm ya and let ya know just to see what it is.

If they have good experience with tuning the older obd1 stuff and back there tunes then thats cool.

 

Ok Kool just let me know and yeah they tune obd1 obd2 and all the way to anything new. And they have proof that their chips and tunes out perform everyone else. ok well I'll check back later tonight g2g get ready for work gotta be there before 3.

 

if fasteddis crank is not marked up and only needs a polish job the machine shop bill for a polish only should be around 60 bucks

 

It cost about 75 bucks to ship that puppy out there....

 

yeah so it'll be just about the same price no matter what I do then lol...that sucks monkey *****

 

Yea your better off just getting one out there itll cost about the same. If you lived close id just give it to ya. Why is it that its always cali where i need to send stuff...lol

 

Why is it always Cali where I want to get parts from?

 

First off, I have to ask... WHY? If you're getting a 3.4 crate anyways, all of this machine work and such is just a waste of money. I can see that you need to have the overbore done because the cylinder walls are messed up, and so you need pistons, but why get the 3.x crank? Just throw a 2.8 crank in there and get the engine running until you can afford the crate 3.4.

Actually, if it were me, I'd just go to a junkyard and pick up a used 2.8, saving myself the costs of the machining to go to the crate engine...

Anyways, I have a V8 set of stamped 1.6 roller-tip rockers I'm willing to let go of... I'm going to go back to the stock 3100 roller fulcrums because the others have been giving me issues with the adjustments... I just need to pull them.

 

I'm trying to pull as much out of this motor as possible. and I'm getting the crate engine for when I'm done with this one...I actually plan on procharger this one hopefully next year with tax money!! Now that's gonna be different...and I don't want to pull another 2.8 to have it machined and cost me even more...because I won't put a used motor in my car with the chance of getting someone elses problem you know. And thanks for the offer of the rockers but if you don't mind me asking why are they giving you problems...what's wrong with them?

 

OK so quick question, can someone send me a link to a new crank shaft from, Autozone, O'riellys, pepboys or Napa that I can use because I'm confused looking at all the ones they have because they say different things like magnetic ignition and such...I need this like asap because I already ordered the cam set, pistons and what not

 

I have one question though. Why a pro-charger? The only reason i ask is because a good handful of people on this forum including me have went the turbo route. Its quite inexpensive if you just want a mild set up and as long as you can weld your golden for the reduced cost. Either way you'll have to tune the thing if its boosted period so that cost is no different and with the options on turbos out there you can get a good quality one for a reasonable price compared to a pro-charger that you will have to fabricate to work right anyways. Just my 2 cents..

 

no ones done it yet and because I stay in cali I can still legally smog the car, I'm going to be doing bracket racing when it's all done as well. And with the procharger all the power is right there at idle, don't have to worry about boost lag and such. and the procharger will require less tuning. and my neighbor is a fabricator he's going to be doing the brackets for me which isn't going to be much at all and on low boost it'll have plenty of power and drive just like stock while cruising...and I want it to be a sleeper!!!!

hey since you're on could you help me with the crankshaft situation I'm having?

 

Ahh I forgot your in cali. Yea the charger will work for ya good. A few people have started doing builds like that but I dont think Ive ever actually seen one complete and running although im sure there are a few out there somewhere. But I do have to add turbos dont make it so you cant have a good 1/4 mile time. I had almost no lag at all at the track last year. I riped out some 1.70's 60 foot time. Granted I was launching the car at 2800Rpm but it took off like a bat outa helll..lol Just watch the vid on my sig.

I totally forgot you needed a crank. Sorry. I have a 3400 crank and a 3.1L crank from my original engine. That original engine is stashed at my parents pole barn as my garage here at my house is pretty full with junk and cars. I will try to get that crank on sunday and I will let you know either way if i got it or not on sunday.

 

yeah, us cali guys have to be smart about it sometimes lol and I've seen the video...your car is the bat out of hell especially when you blew the dyno hose on your other one... and don't worry about you crank I'm just going to buy a new one from one of the auto parts store that I listed above that's why I asked if you could help me...all I need is a link...it's difficult to choose because of the different details they have on the cranks it's only like 3 of them and they are all from the same company I believe!

 

That was project89 that blew the dyno hose. His old car looked just like mine else then mine is a 91 so it has the different ground effects on it. He would be the guy that inspired me to do what I have with mine. And hes also the reason im freaking addicted to making it go faster and faster...

Where were you looking at getting one from? What store

 

what head gaskets can I get that'll raise the compression?

 

oh ok my bad...and I was looking at autozone, oriellys and napa mostly!

 

umm to be honest if you want to raise up the compression youd be better to have the heads milled down a tad. I cant remember to be exact but iirc its hard to find thinner head gaskets then the .040s that felpro sells for our stock replacement.