how to build up an engine for mild boost? - Boost Forum

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how to build up an engine for mild boost?
Tuesday, January 22, 2008 9:28 AM
i have a 2002 Z24 with the GMPP SC....

at 92k miles my engine started ticking, now at 94k it is getting pretty bad and i am told it is most likely a bad wrist pin.

so i need to replace at least 1 piston and rod.... so i figure i might as well take the opportunity to go with forged pistons and rods in all 4. and then thought about a forged crank too. but was told that is a waste of money, and stock is plenty.

But figure if i am doing all this and going this far, i might as well have it bored/honed and all.. treat it to a full rebuild... (looking for a good shop to help with this part, only so much i can do in my garage)

But my SC is ready for a rebuild as well... and i am about to send it to have it remanufactured, and S-Ported, and a smaller pulley installed. So i figure i will have a SC putting out alot more boost, i should build my engine to compliment it....

So what all do you suggest i do to my engine? (this is my driver car, not a strip-only racer) I am not looking to run 10's i just want it fast, fun, and reliable (able to take my abuse and not flinch) I drive ALOT for work. i can put 600 miles on my car in a few days for work easy, and i like this car cuz it makes my drives enjoyable. I just want to make sure it stays that way... putting a rod thru the block 300 miles from home because i was teaching a punk that an aluminum spoiler and chrome wheels does not make your corolla fast, would NOT be enjoyable.


my poor baby is sick... someone help me...
(2.4L engine in my cavy is ticking bad... need to make it stop)

Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 9:43 AM
I understand that 2002 2.4L engines used a 9.7:1 compression piston... my SC seems to work just fine at his compression, but i know alot of guys go LOWER compression for boost.... but i have always known that higher compression makes more power..... so what do you guys suggest? stay at 9.7? or go up or down?

Also how small of a pulley should i run on a newly rebuilt and s-ported SC?

remember, this is a street car. mostly long free-way runs... 100-300 miles in a single run normally.... and then all the normal city driving in between....

Reliable, fast, and fun are the main objectives here.... in that order.

Gas milage is a concern, but as you notice it didnt make my top 3. I dont want to get 15mpg... if that was the case i would buy a vette or something... but dropping a few mpg in exchange for a bunch of horses doesnt bug me too much.


my poor baby is sick... someone help me...
(2.4L engine in my cavy is ticking bad... need to make it stop)
Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 9:45 AM
I vote is a bad rod bearing...



Proud member of Jbody of Kentucky ... Click on sig to go!
Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 9:48 AM
Wiseco 9:1 overbored .020 (or .040 not sure if Wiseco makes those)
Eagle rods
Stiegemeier port and polish/rebuild
Smoothflow modular pulley system
2.6" modular pulley
Snow Performance methanol injection system


2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 9:49 AM
Clevite 77 main & rod bearings


2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 9:51 AM
C2,

i assume that is what you did?
how much did all that cost you? and where did you get it all?
can just any old engine shop do boring on a cavy? or do i want to find a lil ricer shop or something?


my poor baby is sick... someone help me...
(2.4L engine in my cavy is ticking bad... need to make it stop)
Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 9:54 AM
JoeyDaBomb wrote:I vote is a bad rod bearing...


Same here.


Do not go with anything lower than 9.5:1 compression ratio pistons.



Edited 1 time(s). Last edited Tuesday, January 22, 2008 9:55 AM


FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!

Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 10:07 AM
Wiesco will make pistons in what ever compression ratio you need and what ever over bore you need. Have your block measured at the machine shop and have them only bore it enough to get a true bore. They will determine from the measurments they take how far out of round it is and how much should be removed. You do not want them to bore it any more than needed because then if something bad happens and they need to rebore it again they still can.

No need for a forged crank. Pistons are a great idea. They are more likly to withstand detonation than stock ones but they are not bullet proof. You need a wideband to keep an eye on your AFR to help prevent detonation from running lean.

I would actually consider a 10.0:1 compression ratio piston. This should slightly help your gas milage especially in long part throttle highway trips.



FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!

Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 10:18 AM
@ken soggs: Not yet but I'm working on it. If that's what I did I wouldn't be running a 14.8, that's for sure. I have Wiseco 9:1s(stock bore) and eagle rods and clevite bearings, just need to do the rebuild and get a meth injection kit. My stuff cost real cheap ($210 for rods, $200ish for pistons, 62mm TB $100), got most from people parting out their cars.

What's wrong with 9:1's?


2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 10:21 AM
ok i have some people telling me to use 9:1... some saying 10:1... some saying nothing under 9.5:1


can anyone back up their suggestions.... i know in normal aspirated engines, higher is better.... but i always see boosted cars running lower compression....

so can anyone explain why all of this is and what i would gain or loose from going up or down?


my poor baby is sick... someone help me...
(2.4L engine in my cavy is ticking bad... need to make it stop)
Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 10:27 AM
Personally I don't see why you guys with a GMSC blower lower the compression at all. I'd just build it with slightly higher compression, forged pistons and rods with good rings, a nice set of cams, good headgasket, ARP studs, Clevite bearings, go over the oiling system and an alcohol injection kit set to come on at higher PSI's to help avoid detonation.

The reason for going lower compression is to run very high pressures on street gas.... i.e my ridiculous need to run 30 psi on 94 octane. Impossible at stock compression without a ton of bandaids and a daily prayer to the boost gods.

You don't want the supercharger which is already not the strongest unit to make up for the engine having lower compression and therefore carrying the load of getting the car moving. Keep in mind when you port the blower and do any kind of flow mods the PSI it will create drops due to less restriction, but flow goes up. This is good.

I'd personally want to go with a 10:1 piston, port the blower, put in some nice cams, address the head a tidge and mildly port it, and use the alcohol to help out at higher boost / rpm levels.

I think you'll be plenty happy with that. Also, be careful to not overspin that blower.

Oh, and tune it. Please. The GM tune leaves a ton of room for error in terms of timing and octane used. (I guess they assume that sometimes somebody will be stupid and put 87 octane in... and they didn't want to warrenty that mistake so they tuned for it.)

Good luck.

-Chris-



-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...

Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 11:16 AM
Sweetness lives and explains what i said in the other thread a hell of alot better.
Thanks.



Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 11:34 AM
What is wrong with 9:1 is that you will loose power from lowering the compression. The m45 will not put out enough boost to warrent the need for lower compression pistons. The only advantage is they are what wiseco stocks. Any other compression ratio will be a custom order and likly take a 6 weeks to get. But if you are building it just wait 6 weeks and get what you really want in there.

I agree with sweetness 110% on what he said.



FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!

Re: how to build up an engine for mild boost?
Tuesday, January 22, 2008 1:34 PM
I have my 9.5:1 pistons for sale so I can get a set of 10:1's

My 9.5:1 where originally for a turbo build, but now that I have a SC I am changing them



Jason
99 Z24 Supercharged
157hp/171tq - NA
LD9 for Life
Re: how to build up an engine for mild boost?
Wednesday, January 23, 2008 6:17 AM
if you want a good starting point for boost look up http://www.importperformanceparts.net/ they have a kit for $999 that includes......
Complete Gasket Set
Performance Copper Head Gasket
ROSS/Wiseco Forged Pistons
(90, 90.5, 91mm bore)
(9.5-1, 10.5-1 comp ratio)
Performance Moly Rings
Performance Wrist Pins - Ultra Lite 79 grams
(stock pins weight 112 grams)
Federal Mogul Main Bearings
Federal Mogul Rod Bearings
Balance Shaft Bearings
Timing Chain
Lifters

and gives you an option to also get
Eagle Connecting rods=$315
TOGA HP Intake & Exhaust Valves=$12.99

So for a pretty damn good motor you should look there. You could also do it the old fashion way and buy everything seperate but I see this as something with potential

"As I lay rubber down the street, I pray for traction I can keep, but if I spin and begin to slide, please dear God protect my ride." -Amen
Re: how to build up an engine for mild boost?
Saturday, January 26, 2008 10:55 AM
AJ B wrote:if you want a good starting point for boost look up http://www.importperformanceparts.net/ they have a kit for $999 that includes......
Complete Gasket Set
Performance Copper Head Gasket
ROSS/Wiseco Forged Pistons
(90, 90.5, 91mm bore)
(9.5-1, 10.5-1 comp ratio)
Performance Moly Rings
Performance Wrist Pins - Ultra Lite 79 grams
(stock pins weight 112 grams)
Federal Mogul Main Bearings
Federal Mogul Rod Bearings
Balance Shaft Bearings
Timing Chain
Lifters

and gives you an option to also get
Eagle Connecting rods=$315
TOGA HP Intake & Exhaust Valves=$12.99

So for a pretty damn good motor you should look there. You could also do it the old fashion way and buy everything seperate but I see this as something with potential



Sounds real good.... but it says that kit is only for "Chevy Cavalier 2.4L 1996-00" and they dont have a kit for the 01-02 2.4L.... should i still be able to use this on my 02? i would think so... but i dont trust my opinion. they have just about everything else for the 01-02... just not this kit... so i wonder if there is a reason for it.


my poor baby is sick... someone help me...
(2.4L engine in my cavy is ticking bad... need to make it stop)
Re: how to build up an engine for mild boost?
Tuesday, January 29, 2008 5:15 AM
people generally dont trust their opinion when they are not to sure but once you do things to a vehicle, sometimes you will never go back. this kit will work on your 2002(as long as done right). And you will have quite a bit of getty-up-and-go. and a pretty darn strong motor. I have a 1999 Z24 with the 2.4 and no problems thus far

"As I lay rubber down the street, I pray for traction I can keep, but if I spin and begin to slide, please dear God protect my ride." -Amen
Re: how to build up an engine for mild boost?
Tuesday, January 29, 2008 6:33 AM
ok... but what about compression? i only have the choice on 9.5:1 or 10.5:1 with this kit... i have 9.7:1 now... most people suggest 10:1 that isnt an option here... so do i DROP compression and go 9.5:1..... or go up to 10.5:1....

or do i just scrap this kit and find something with 10:1 and pay a lil more.


my poor baby is sick... someone help me...
(2.4L engine in my cavy is ticking bad... need to make it stop)
Re: how to build up an engine for mild boost?
Tuesday, January 29, 2008 7:53 AM
I would buy all the stuff seperate. That realy does not sound like it would be any cheaper. By the way when you buy pistons from wiseco you get the rings and wrist pins as well.



FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!

Re: how to build up an engine for mild boost?
Tuesday, January 29, 2008 8:01 AM
You can raise the CR a little by having the cylinder head shaved and using a Cometic NA headgasket. The Cometic headgasket is thinner than a stock felpro headgasket.



Jason
99 Z24 Supercharged
157hp/171tq - NA
LD9 for Life
Re: how to build up an engine for mild boost?
Tuesday, January 29, 2008 4:38 PM
So wade i take it your not a fan of the kit?

"As I lay rubber down the street, I pray for traction I can keep, but if I spin and begin to slide, please dear God protect my ride." -Amen

Re: how to build up an engine for mild boost?
Wednesday, January 30, 2008 5:27 AM
is it true that the older (96-99) Z24's had smaller combustion chambers in the head? If so does anyone know how much smaller or what kind of CR change this would make? I know they had the 9.5:1 pistons... but with higher compression heads, could this have ended up with the same combined compression as the 2002 engine with 9.7:1 and the larger chamber heads?

with this in mind.... and seeing as that "kit" is designed for the 96-00 (says nothing about 01-02) maybe they are giving you compression figures based on the stock head (smaller chamber) and that if you used it on a 2002 with larger chamber, you would be at a lower compression (maybe 10:1?)

Also.... what about head gaskets.... i know stock gaskets are the weak link in our engines under boost. but how are the aftermarket gaskets? the ones designed for this kinda stuff? and are you safer to go thicker or thinner on the gaskets?

i was just thinking i could tweak compression slightly with heads and gaskets... i could use a 02 head and thicker gaskets to drop compression (if i wanted to go with the 10.5:1 and bring it back to around 10:1)

Also, how much if any performance can be gained by boring the 2.4L out? I will have my engine bored anyway for the new pistons... so just thinking maybe i should go with a larger bore to gain some displacement. like how many liters can be gained by how much of an overbore? like will going 30-40 over give you much at all, we talking like 0.1 liter or what? and how much meat do these blocks have for safe boring?


my poor baby is sick... someone help me...
(2.4L engine in my cavy is ticking bad... need to make it stop)
Re: how to build up an engine for mild boost?
Wednesday, January 30, 2008 10:03 AM
I could be wrong but I think the combustion chamber volume in the all 2.4 heads are the same. I would not worry so much about running as close to a 10:1 compression as you would proably be fine with 10.5:1. Yes you could use a thiicker head gasket to lower it some How much lower I do not know. You are not going to gain much at all by boring the block .030 or.040 as oposed to .010 You would never feel the gain

Cometic and SCE make head gaskets but keep in mind the headgasket is only as good as the person installing it and head studs or bolts used.



FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!

Re: how to build up an engine for mild boost?
Wednesday, January 30, 2008 10:20 AM
ok... new bit of info here...

someone just pointed out to me that their Z24 had the same noise that mine did (the ticking noise) and they too assumed it was a bad wrist pin... and tore their engine out to fix it, only to find it was nothing but a bad crank bearing. He said that i should drop my oil pan, remove the rod caps and inspect my bearings before i go swapping engines and dumping $1000 into my bottom end.

Does anyone else agree with him? he says 3 hours to inspect bearings is well worth saving $1000 on replacing a whole bottom end.

the big arguement now is "rod bearings make more of a low pitched knock coming from bottom of engine, and wrist pins make more of a upper engine tick" This guy told me his engine sounded like a tick from the top... but everything was fine excpet for the rod bearings. and says sounds alone can be misleading.

some believe the rod bearings are a waste of my time... and some say "it is well worth a try"

so what do you think?


my poor baby is sick... someone help me...
(2.4L engine in my cavy is ticking bad... need to make it stop)
Re: how to build up an engine for mild boost?
Wednesday, January 30, 2008 4:27 PM
I think, what harm could it cause? if you trust the mechanic and he is good no reason not to take a look but then again if your goal is to rebuild and produce a better engine......in the long run you are going to need to get it done so simply put what are your goals? whats the budget? and how much you trust the mechanic? but by looking at other posts I know you have a supercharger, so does that mean you plan on keeping the car for a long time or was it just for fun?

"As I lay rubber down the street, I pray for traction I can keep, but if I spin and begin to slide, please dear God protect my ride." -Amen
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