Some insight into the 3.4L OHV RWD motor

[nightrider2]

Re: Some insight into the 3.4L OHV RWD motor

when i get my MS is I think I'll have some VERY impressive numbers to show

[wolf]

Re: Some insight into the 3.4L OHV RWD motor

anyway, with a proper tune you would see improvements in fuel economy. once i get my car tuned ill let you guys know if the car gets better gas mileage. im hoping cause rite now im at 12mpg or so (ugh...ferkin cam).

what kinda milage were you getting before the cam swap?

[nightrider2]

Re: Some insight into the 3.4L OHV RWD motor

With out the cam, you typicily only lose 1-2mpg,but you still have to tune it one way or another.

[crewgirl]

Re: Some insight into the 3.4L OHV RWD motor

OMG my head is spinning...............
One of my biggest pet peeves is people who read the first two and last two pages of a thread then post a million questions that have already been answered, therefore I have read and tried to understand every post in this thread.

So here goes my main question......... Has anyone even tried porting the cast heads that came on the 3.4? I had given up on modding my 3.4 until recently, and then my wonderful husband found this site one day and I've been in research heaven.

I've only seen one post regarding taking the original 3.4 heads to a machine shop and that post went to the tune of "too expensive". But I work at a BAD@SS machine shop (raymacraceengines.com) so the money factor isn't a factor for me, it's a perk of the job. My car has had a terrible miss since I got it and a compression check revealed that the # cylinder has virtually no compression. We tore down the upper end and I took the heads in to work for a look over (the miss was not in the heads) but while they were there they got a competition grade valve job and some compression milling. Theoretically this should add 8-10 hp. (These numbers are based on calculations made by the cylinder head guru and not actually verifiable since I never dynoed the car before I did it.)

Here's where my head is at..... If I were to have the heads and intake ported, while keeping in mind the compression limitations of the stock pistons, do you guys think this would be comparable to the swap things you guys are doing? The guys I work with are used to working on v8's that have HUGE displacement so they scoff at 200 ci. But my research is turning them around. Doing the porting would be the more cost effective solution for me since I don't have to pay for the labor.

Any thoughts?

[FireShadow]

Re: Some insight into the 3.4L OHV RWD motor

I believe that somewhere in the middle pages =) it says that the 3400 heads/intake flow as well or better as is than a fully ported set of the 3.4 stuff.

[crewgirl]

Re: Some insight into the 3.4L OHV RWD motor

Ok, so in theory I can port the stuff my engine already has and save some money for other mods. Once I track down and eliminate the miss I'm going to have this done and I'll let you guys know how it turns out.

[FireShadow]

Re: Some insight into the 3.4L OHV RWD motor

Hmmm. I think we are on different tracks here. If you are going to do engine work anyways, especially p&p stuff, then why not do it on the 3400 parts? If you have the available shop and expertise it isn't that expensive and probably will wind up doing more for you than other mods. Just my 5 cents (adjusted for inflation).

[black34v6]

Re: Some insight into the 3.4L OHV RWD motor

Ok, so in theory I can port the stuff my engine already has and save some money for other mods. Once I track down and eliminate the miss I'm going to have this done and I'll let you guys know how it turns out.

basically you can p&p your iron heads. you will be - with ported iron heads - where i was when i swapped on the 3100 parts. The thing that I must stress is that if you P&P the iron heads, you will STOP the performance gains there.

if you manage to get 170rwhp/207rwtq out of P&P'd iron heads, you wouldnt be able to take it much farther because that much porting would pretty much max out the iron heads potential. The aluminum heads START (without any P&P work) at 170/207 and you can increase the hp/tq of your engine by porting and polishing the aluminum heads.

I wrote this as to open everyone's eyes to just how bad the design of the iron heads are. That being said, if you want to P&P your iron heads, its your car - more power to you. But i think you will be dissapointed as you wont get as much performance out of the car as you want...

AND -- you will be limited to the 4500 rpm "zone" -- the flat spot that every 3.4L owner faces because of the design of the intake and heads.

I can get power all the way to 5500 rpm - where the iron head 3.4 "flattens out".

just something to think about.

[black34v6]

Re: Some insight into the 3.4L OHV RWD motor

what kinda milage were you getting before the cam swap?

corrected -- im getting about 10mpg (estimated) with the current setup + no tune. before the cam i was at like 15-17 mpg (about the same as a Z28).

the car has always run rich after i changed the heads, the cam just made the situation worse. im hoping to get the swap (megasquirt) done soon so i can tune / dyno / track the car asap.

[crewgirl]

Re: Some insight into the 3.4L OHV RWD motor

I understand that by doing the machine work to my iron heads, I'm simply getting them to the starting flow point of the aluminum heads. But, here's the thing, I haven't done any performance mods to my car yet. The heads and intake etc won't be free, but the port and polish will be, for me. There fore I can take the other money and install things like a new cam and headers and ram air, etc. Plus our head porter guy is really good at making things flow the way they should without taking them to the absolute limit. By doing it this way I save a little money now and if I'm still not happy I can get the 3400 parts and do the swap later. Right now I'm looking at starting this project during late summer when the machine shop slows down a bit (free work takes a back burner to paying customers). I will post the flow numbers when I get the work done.

I don't know if I said it before but THANKS for this thread!

[black34v6]

Re: Some insight into the 3.4L OHV RWD motor

I understand that by doing the machine work to my iron heads, I'm simply getting them to the starting flow point of the aluminum heads. But, here's the thing, I haven't done any performance mods to my car yet. The heads and intake etc won't be free, but the port and polish will be, for me. There fore I can take the other money and install things like a new cam and headers and ram air, etc. Plus our head porter guy is really good at making things flow the way they should without taking them to the absolute limit. By doing it this way I save a little money now and if I'm still not happy I can get the 3400 parts and do the swap later. Right now I'm looking at starting this project during late summer when the machine shop slows down a bit (free work takes a back burner to paying customers). I will post the flow numbers when I get the work done.

I don't know if I said it before but THANKS for this thread!

lol...no problem - i put this up to help people. anyway, i hear what you are saying. The 3400 swap REQUIRES headers to be used anyway, and a cam is never a bad idea. the ram air is a waste of time -- many of the v8 guys found that a ram air setup wasnt any better than a cold air setup...

just a little more infor for ya :)

[crewgirl]

Re: Some insight into the 3.4L OHV RWD motor

LOL The Ram Air thing is more of about being able to say, "Yeah I got Ram Air". It sounds cool.

[crysmatic]

Re: Some insight into the 3.4L OHV RWD motor

the 3800 uses a split crank to make it even firing (obviously). this also makes the firing order 1-6-5-4-3-2. every other cylinder that fires is on the same bank...which is wonderful for intake and exhaust tuning. it's the twisted runners on a v8 dual plane intake vs a ferrari intake; one plenum feeding the bank directly below it (ferrari v8s have 180° cranks).

imagine my surprise when i found out the alloytec uses a split crank, even though it's a 60° v6. it uses it for intake tuning as well. nissan's vq has been using it for years. the 3400/3500/3900 also use split cranks. it opens some custom intake options.

re your original post. it's the heads that limit rpm. the short runners just don't give resonance tuning in the low/midrange (they're not a restriction). 340*85/0.305/rpm=resonance tuned intake length (in inches) from the valve to the runner mouth. a 6" total length is tuned for 15,800 rpm! hth

good luck with the ms tuning! i expect good things:)

with better flowing heads need less cam to make power. a pocket port helps flow tremendously without hurting velocity. russell: do you have flow #s for the 3100, the latest heads, or the small valve 3500 heads?

if gm put as much money into a single v6 as they did with the v8...we wouldn't need superchargers or v8s in mid sized or fwd cars.

[black34v6]

Re: Some insight into the 3.4L OHV RWD motor

dont have flowbench numbers on me at present, i can ask the person that gave them to me originally to send me another copy of it.

[The_Beast]

Re: Some insight into the 3.4L OHV RWD motor

Can anyone get me a list of the gaskets needed? I want to have everything I need (yeah right) before I start this. And, if possible, can you tell me which gasket for which engine (head gasket for 3400 for example)? Thanks.