Hey Guys,

I am interested in upping the compression in my magna a bit to give it a bit more Ooompf. Now besides an aftermarket ECU, is there anything else that need's work on internally? Or is there a certain point I can go to on stock internals? And if the internals need to be tampered with, any idea's on rough pricing?

I will appreciate any help or suggestions you guys can offer.


Thanks, Lukas.

an aftermartcket ecu will not increase compression, the only way to increase the compression is to pull the engine down and start changing pistons, head gaskets, head work etc, expect a few thousand

did you mean ... advancing the timing ? or retarding it.... i can't remember which one is best for N/a.... but yeah you can alter the timing through an aftermarket ecu... ie. make it so your engine will only run on 98 ron

also, jason semmler with the quick magna has slightly increased his compression ratio, although i dont see how this can be done without spending over 1K



later :cool:

Hey Guys,
I am interested in upping the compression in my magna a bit to give it a bit more Ooompf.
what is your stock ratio?

++++
Greetings All.

6g72 SOHC- 9.0:1
6g74 SOHC- 9.0:1
6g74 SOHC Ralliart Spec - 9.4:1
6g72 DOHC MIVEC - 10.0:1

The only way to increase compression in magnas is to find wrecked ralliarts or buy totally new pistons...no matter what expect over $1200, you will also NEED a piggy back computer...If you are going to go higher compression, i HIGHLY recommend getting the head port and polished or even extrude honed if possible, and maybe a set of cams...

Hope this helps!

Cheers,
--Tonba
++++

9:1 apparently

This is for a TJ Sports BTW

6g72 SOHC- 9.0:1
6g74 SOHC- 9.0:1
6g74 SOHC Ralliart Spec - 9.4:1
6g72 DOHC MIVEC - 10.0:1


the 3.0 in my 2nd gen has a 10.0...

are those the ratios for 3rd gens only?

the 3.0 in my 2nd gen has a 10.0...

are those the ratios for 3rd gens only?

No the 3.0 in your 2nd gen is the 6G72 SOHC at the top of the list, not the DOHC MIVEC at the bottom, so you're only 9.0:1

Also..

From what Jason S has said the reason the Ralliart ended up as mild mannered as it did was (partly) to keep it running on regular 91RON ULP, so if you go above 9.5:1 CR expect to require 95RON fuel.

That said, it's a good mod for power, though, if expensive.

No the 3.0 in your 2nd gen is the 6G72 SOHC at the top of the list, not the DOHC MIVEC at the bottom, so you're only 9.0:1

Good Sir I call you not a liar nor a simpleton but the manual my automated chariot sallied forth with proclaims a compresion ratio of an impressive 10.0:1

Fair enough then :D

I actually didn't read your post correctly anyway, I thought you were asking a question when you were makeing a statement. Sorry :shifty:

Good Sir I call you not a liar nor a simpleton but the manual my automated chariot sallied forth with proclaims a compresion ratio of an impressive 10.0:1
Heh heh... nicely said.

2nd gen V6's had 10:1 hence the knock sensors and potential gains from higher RON fuels.

Heh heh... nicely said.

2nd gen V6's had 10:1 hence the knock sensors and potential gains from higher RON fuels.

I always pump 98 octane. my mate with a gt4 celica always wonders how he cant seem to leave me for dead... once I get the suspension done, new fuel filter, whack in the K&N panel filter and get my TB flowed, this verada is going to be the nicest car ive ever driven.

your auto keeps up with a gt4, **** thats alright, the verada should've had more manuals, such a nice interior etc...

You should:

Measure your cylinder and head volumes to calc your compression.
Remove the head(s), deck them, port them, back cut the valves, measure your cylinder and head volumes to calc your new compression. You can shave more off the head to increase the compression a few points here. Much easier than changing pistons and you get ported heads for the price of 6-high top pistons.

Have change from $2K. + piggyback ECU. Recommend Haltech!!

++++
Greetings All.

6g72 SOHC- 9.0:1 24v only 6g72 SOHC 12v/DOHC 24v is 10.0:1
6g74 SOHC- 9.0:1
6g74 SOHC Ralliart Spec - 9.4:1
6g72 DOHC MIVEC - 10.0:1

The only way to increase compression in magnas is to find wrecked ralliarts or buy totally new pistons...no matter what expect over $1200, you will also NEED a piggy back computer...If you are going to go higher compression, i HIGHLY recommend getting the head port and polished or even extrude honed if possible, and maybe a set of cams...

Hope this helps!

Cheers,
--Tonba
++++

Just had to correct that there dude ;)

your auto keeps up with a gt4, **** thats alright, the verada should've had more manuals, such a nice interior etc...

Keeps up with, he is about a second quicker on the quarter, and about a year after we did that his engine died. so it might not have been a healthy gt4...

Yeah manual conversion is on the list right after the suspension since i cant do any ENGINE PERFORMANCE modifications. thanks to the nsw government. maybe manual conversion, maybe tiptronic.

You should:

Measure your cylinder and head volumes to calc your compression.
Remove the head(s), deck them, port them, back cut the valves, measure your cylinder and head volumes to calc your new compression. You can shave more off the head to increase the compression a few points here. Much easier than changing pistons and you get ported heads for the price of 6-high top pistons.

Have change from $2K. + piggyback ECU. Recommend Haltech!!

Who can do this sort of work? Does anyone have experiece in this sort of work on our engines?

Who can do this sort of work? Does anyone have experiece in this sort of work on our engines?

To my understanding, only really RPW have gone to any length with it for the magna's. And after speaking to dave a bit, I can see the budget for this getting blown out of the water. but hey, im gonna try anyway. I just want to see how far i can push a 3.5 in a high comp application power wise.

Give Dallas from Street Torque in Alice Springs a call. He built up a 13:1 super high compression 6G72 3L motor for Booya (Ben) about 18 months ago so he'll know the ins and outs of uping the CR too.

Street Torque - 08 8952 7755 - tell him Brendan sent you :D

Give Dallas from Street Torque in Alice Springs a call. He built up a 13:1 super high compression 6G72 3L motor for Booya (Ben) about 18 months ago so he'll know the ins and outs of uping the CR too.

Street Torque - 08 8952 7755 - tell him Brendan sent you :D

If you talk to Dallas, pls post up a summary of what he has to say (or get him to write his own post) because people on this forum are interested. TIA.

Good Luck Arti!
Sounds like a nice N/A Power boost :D

yeah if theres a way to up the compression on my 3l SOHC 12v without tearing it right down, id like to know.

yeah if theres a way to up the compression on my 3l SOHC 12v without tearing it right down, id like to know.

10:1 compression is nearing the limits of pump fuel without advanced ECU control and/or efficient head design.

You can shave more off the head to increase the compression a few points here.
What's the chance that you might have issues with the inlet manifold not fitting / lining up on a V engine? I guess we're not talking about much being removed.

10:1 compression is nearing the limits of pump fuel without advanced ECU control and/or efficient head design. I do run Vortex 98, but yeah I figured an ECU would be the key to ANY of the tracks im chasing.

Of course doing any engine work will have to wait till im off my green P's so a set of extractors, full exhaust and cold air intake would be first. I dont want to supercharge or engine swap if i can help it so research time is in abundance.

What's the chance that you might have issues with the inlet manifold not fitting / lining up on a V engine? I guess we're not talking about much being removed.

Just build a custom intake manifold, maybe in conjuction with somthing like what RPW did. Or make a 2 stage intake runner setup to increase efficiency of the intake over a bigger rev range :P Will cost time and money but I'd imagine it would be worth it.

I have been thinking of drawing up a 2stage design on autoCAD (not taking into account exact measurment). Basically underhood room is a limiting factor.

Basically underhood room is a limiting factor. now that to me sounds like an excuse for a custom vented carbon fibre bonnet...

now that to me sounds like an excuse for a custom vented carbon fibre bonnet...

Yes the options are almost limitless, just they cost too much lol .

I wonder how a twin plenum setup like the one in Z32 300ZX's would work on a Magna?? Probablly too much trouble getting the throtles to open in sinc. Or perhaps a flat plan plenum design similar to the HFV6 alloytecs or VQ35's (?) in the 350Z, allowes greater plenum volume in tighter underhood conditions :P

Back to CR topics.... lol

What's the chance that you might have issues with the inlet manifold not fitting / lining up on a V engine? I guess we're not talking about much being removed.

No idea, haven't done it (yet). I reckon it'd only be a few thou of an inch to chop anyway. Shouldn't be any dramas from that.