Inliners International Forums General Discussion Blown and Injected Blow Through Tuning

Well I got some time to play with the car again. I first just tried making a vent tube extension. This seems to work well dropping my AFR's at cruise by 1 point to mid 11's. On the First WOT pass The AFR dropped hard to low 10's once i got past 4500 or so it began to cut out, but the AFR stayed low even dipped into the 9's. Although on other passes it sometimes stayed around 12 @ WOT so i think the vent tube although effective is inconsistent for me. Ill look into the PCVR's at this point and tune WOT that way, also plan to boost Refrence the PV.

Is it possible I am blowing out the spark? The plugs were gapped at 40? i think should I go smaller like 25-30? Or possibly valves out of adjustment?

Another issue that popped up is under WOT it takes forever to shift, but shifts hard when it does so I think the TV cable may be a bit tight.

i can't help alot with the carb, but can with the trans. at what rpm does it finally shift @ wot. if the rpm is too high, then you need to mess with the governor. at low speeds does it go thru the gears ok? my trans guy says to test the tv adjustment, get the car going about15 mph in 2nd. then floor it, the trans if adjusted correct should downshift.

with the ignition, are you using a hei? if not get one. they are cheap and parts are readily avail. i am running a hei , plugs gapped at 45 and no spark loss.

I dunno i haven't stayed into it long enough to find out, ill have to watch next time. I doubt its the governor the trans worked fine over the last 2 years behind my v8. I would think though that if the TV cable it to tight the pressures would be to high holding the shift out longer? Then again my v8 would spin 6500 maybe im just not used to the lower rpm of the 6 yet. Driving around it feels fine shifts firm.

I have a Petronix Ignitor in the stock distributor. Im beginning to think its a valve adjustment issue?

Glad to hear your running it more.
What boost pressure are you seeing?
.040 plug gap is a little big.
.035 should be fine,until you turn up the boost or run a lot of methanol.

The valve out of adjustment issue?
How are you adjusting them?
Is it running rough?

On the boost referenced Holly regulator, have you hooked up gauges to see what your fuel pressure is compared to you boost pressure?
What is your baseline static fuel pressure?
Something to check.

Do you have a choke valve on the carb, could be partially closing under boost?

MBHD

a hair over 3psi, dead on for the 3.36psi spring.

Ok ill close them up a bit. I did inspect them and saw no signs of detonation on the plugs themselves.

I set them according to the motors manual on initial start up but they made noise, then we did a hot adjust on them, back off till they clatter, take the slack out and tighten 1 full turn. I still have a few 3 i think that are rattling loud. Im going to pull the cover again and see if maybe the lifters went dead?

I have a gauge on the regulator itself, static pressure is 7psi, I will double check that its not leaking, maybe run a line and strap a gauge on the hood and see what its pushing under boost. Then again if it was a Fuel Pressure issue wouldn't the motor go lean? Im going to hook up the laptop and log the AFR's and post them next time im out.

Nope no choke, as for the tranny im going to pick up a pressure gauge and make sure its adjusted correctly sicne i had to make a custom mount for it. I really iwsh my buddy would break down and sell me his built 250, @ 3psi its hard to feel any significant power gains, i guess well see once i get the tuning down.

I was thinking your regulater might be increasing your fuel pressure too much therefore giving you too much fuel, overcoming the needle & seat.

Might try a little less base line fuel pressure also, just to see if it changes your A/F mixture.

BTW, how much total timeing are you getting?

Hooking up a fuel pressure gauge just to see your pressure under boost pressure is a good thing.
Goodluck on your next logged runs.

MBHD

True ill drop it down to 5psi base and see where we stand, I don't have a dial back light but ive been meaning to pick up some timing tape for the balancer.

Cool,do you have an idea on how much total timeing you want to give it?

MBHD

not really im used to tuning my N/A V8 and it liked 32total but with the 6 i have no idea what i should shoot for.

Since you are not running that much boost I would think you could go to the mid to upper 20's-low 30's.

Need to get that intercooler installed though.
That should help w/you to get higher total timeing.

My Syclone likes about 20-24 degrees total depending on conditions,gas used, but that is a different animal, computer controlled, knock sensor ,etc.
Plus,, stock they (Syclones/Typhoons) boost to 14 psi,my boost I set to 18-24 psi with my chip I run.
Now w/you only running 3 psi boost pressure I could see you running upper 20's - low 30's degrees total timeing, on pump gas.

Just remember,, my Syclone has a knock sensor so when it hears knock,the ECU will pull out timeing therefore saving my engine from blowing up.

Keep us posted on your findings.

MBHD

Will do, not much time to work on the car lately, mostly wanting to get it running just reliably on low boost, got a trip end of July and id rather not have it blow up before then lol...

with our sixs having poor combustion chambers, they like timing. i'd bet n/a timing could go as high as 36-38 or higher. old BB chevies like timing too. once the boost comes into play start taking out around 2 degrees per lb of boost. i have had bad luck with pertronics kits and high performance use. one reason is timing control @ higher rpm. the old mechanical distrib with worn out centrifical mechanisms would tend to scatter the timing at higher rpm.

revod, are you also using a performance coil?

with the old motor , what were your shift points? i bet the v8 liked them higher than 5k rpm, the governor may need to be adjusted to bring them down. tom

The transmission was a stock rebuild for a mid 80 Monte Carlo, its been so long since i drove the v8 i dont remember but I would say it shifted WOT around 5200 or so. Once I get my mount figured out and line pressures good ill look into adjusting the governer.

I dont have a progressive timing retard but my Digital 6 does have an on demand timing retard for Nitrous I was contemplating using a hobbs switch to activate it and just pull out x ammount of timing all at once when boost hits. I am running a MSD Blaster 2 coil, all the stuff from my mid 12sec v8

the hobbs switch with a set amount of timing pullout will work fine. but if you get the boost up near 10, you may need better timing control.

on the fuel issues, could you be running it too rich? AFR around 10 is for a engine under alot of boost. i only run mine down to 11.25 around 10-15 lbs boost and higher rpm, 4500. maybe you are just flooding it out. on mine a sure sign of a lean was a sort of stuttering under load and finally a BIG backfire if i stayed into it. i would guess at 3 lbs a AFR of 12 would be ok. my cruise AFR is 12.75-13. idle is 13. i can't really go leaner or it runs bad. tom

ok ill take more jet out and shoot for high 11's low 12's. Maybe like MBHD said if I take some static pressure out. I really need to use the laptop anyways to start logging runs so I can keep my eyes elsewhere. We dont plan to boost anymore then 8psi on this motor so what i have now should work fine if we go higher ill pick up a BTM.

Revod, do you have aftermarket lifters or stock? aftermarket use only 1/4-1/2 turns depending on brand. maybe running out of travel.
I would think you need more timing 36-38* total
I don't think you need any boost ref. pv or vent tube ext. at such low boost even to 15-20#
Try smaller plug gaps .025
6# fuel pressure (reg will increase boost amt. and engine will still think it's 6#)
Use 2.5 powervalve !!!
Take on highway and read plugs
Do you know exh temp, if high could be timing.
Check float level, high float can make richer, pulls over to easy.
Also 3# boost is not much, raise boost to lean out, if spring will not go higher use a reg to gain boost.
Check plug wires.


Harry

Its a completely stock 230 with 80,000 miles so its dead stock.

Yeah ill look into timing I was just used to my V8 which didnt like more then 32.

Well the vent tube was just a test as an alternative to drilling out the PVCR's. But im gonna scrap that and work on the PVCR's now.

Gotcha ill give that a shot.

Ive considered putting a smaller PV in.

I will have to make some WOT passes and then shut it down to read them definitely.

No EGT sensor but ive though about getting one.

I've check them I even though about that and set it a hair lower then I normally do.

Yeah I need to pick up a regulator and try raising the boost at this point.

Its got a brand new set on it of stock wires, although I might try and use my 8.5mm MSD's from my v8 on it.

Thanks for the input Harry. Hey my dad wants to know what nights do you guys usually hang out at the shop? Were thinking about swinging by with the Nova. I just need ya to build me a monster 292 like you've got in that 38... lol

I will be getting a 250 that a friend of mine built years ago when he pulls it from his car. He had it bored .30 over, with a decent cam (around 510 lift iirc), full roller rockers, ect.. He built it with hopes to make a quick 6 but got sidetracked stuck the 1bbl on it and stock exhaust lol... its only got 5K on it I plan to swap the rod bolts out for ARP's take out the HV oil pump he put in and stick my turbo setup on it. But it may be 6months or so before hea ready to pull it.

RevOD,,,,,,

I would also suggest a shifting point of 4000RPM or maybe a little lower as to let the torque push the car through the gears.

If your trans shifts anywhere near 5000 RPM or higher you are just slowing the car down because I'd bet your max power w/stock cam/engine is no higher than 4000 RPM.

It is amazing what a engine will do when you put a load on your engine & let the torque push it through the gears,thanks to your turbocharger.

MBHD

Yeah good point, ive been checking into modifying the shift points via the governer. Once I verify line pressures ill play with it.

Played with the car a bit more installed a boost/vac gauge (before i had just a boost gauge). Turns out im pulling 3-5psi of vac which I assume means my #6 PV is open during cruise? Will deffenitly pick up a #2 to replace that. Have a gated MBC that I will install shortly.

Wow, 3-5 inches is pretty low,esp for a stock cam??
If that reading is correct,then, yes, your PV is open during cruise.


MBHD

seems to be I verified it with another gauge. Heres the deal though at cruise around 65 if I roll into it ever so slightly to lightly pass someone it begins to build boost. I think thats why it so low cause im am that close to making boost. So with the new gauge im going to clean up all my vac connections, install the MBC and see what happens.

sounds like the exhaust housing is too small. with it's restriction the turbo is more efficient at taking exh energy and driving the turbine. you vacum reading seems real low for a stock cammed motor. mine runs around 12 @ highway speeds, 15 @ idle. hits zero at just about any throttle push part 1/4 and then boost pressures. i would get rid of the pcv, clean up the hoses ect. do you have power brakes? if you do i bet they won't work very good. get the pv closed and readjust the idle mixtures and you will see more vacum. tom

I dot not have power breaks, and I would get rid fo the PCV but if I do it spews oil all over the valve covers so unless I can seal them up and set up a remote catch can possibly? Now at idle I am pulling 20in or so.

I would not recommend getting rid of the PVC.
Unless you have a big breather in the valve cover that won't blow oil everywhere.
Or you can run an electric vacuum pump to a catch can???

You might have too small of turbine housing like Tlowe said, also,your turbine wheel is too small.
Your engine is a 230, correct?

For now you can try and port the snot out of your turbine housing(really open up the exhaust port/entire turbine housing) if you do not want to spend money on a bigger turbine housing in order to get more exhaust flow.
20 inches @ idle is fine.

MBHD

i added bolt on vents to the side of my valve cover. 20@ idle is what i would expect to see. i agree with hank, open up the exhaust housing to let more exhaust sneak by the turbine. tom

The housing is marked as a .82 a/r. When you say open up the housing how would one go about doing that? Id hate to mess it up, finding another one like it will be tricky. Although I do know where the original .64 housing is i believe.

.64 is going the wrong way. your next step is to go toward a .9X- 1.XX. to loosen the housing, you could as a last resort open it up around the turbine wheel. that is just my opinion though. maybe you can get the old .63 housing and get it opened up to a .9X and try it. tom

Your engine is a 230,,, correct????

If it is a .82 A/R then that should be OK.
By opening it up, I mean to open the exhaust passage in, anywhere it narrows/necks down.

If you can get the old housing for free, practice opening/porting on that piece.
Measure the turbine wheel hole size & compare to your .82 housing to see if they are the same.

Get a double cut carbide cutter tappered cone type. 4" long or 6" Like 3/8 diameter or so.1/4" shank

Just before & right at where the exhaust enters the turbine wheel(hits the wheel for making it spin), it necks down the most, check for casting flaws, thin spots, & relieve these areas.

Only other choice is to send out your turbo center section to have the turbine wheel clipped,,,,& rebalanced,,, but doing so,, you will add a couple hundred RPM before you go into boost.Like if your boost comes in at 2200 RPM, it will come in @ 2400 RPM or there abouts.

So if you are not happy w/how the boost comes in now,, I would not suggest to do that.

MBHD

It is a 230 yes. I dont mind how the boost comes in actualy. And I did some more driving and got on the interstate and will correct myself I am getting near 10in at cruise. Realized the roads I was on before were too up and down to get an accurate reading.

then it sounds like you just need to get the carb adjusted more. worry about the boost later. maybe adjust the boost to atleast 5-6 though. make it worth while . tom

yeah definitely. We got the boost controller installed and pushed it to 5psi. it will sit there while we tune. I did make one or two WOT passes at 5psi and i could tell the difference.

The first pass was fine the 2nd it made a loud howling sound and boost began to drop I got out of it quick. The 3rd pass it boosted fine for a WOT pass. Wonder what made the slip in boost on that one pass? Possible boost leak in a coupler?

a leak is possible. your turbo could also be getting pushed too hard and spinning the turbine at too high of a rpm. i believe the term is surge. hard telling what it is. all i know is if it is truly bad, it will show itself again and you'll get a chance to figure it out. how are the afr's at 5 lbs? tom

High13's low 14's that was durring some short shot blast enough to hit boost and get out of it.

Detonation could be going on.
That is a lean A/F ratio.
Detonation will cause it to loose power & boost pressure.
You still do not have an intercooler installed?
What octane gas are you using?
If you do not install an intercooler, I highly recommend you install a methanol injection kit, ,,it could save your engine.

MBHD

those afr's are to lean, under boost get it closer to 11.5 or so.

hank, i do not think he needs a intercooler with the lower than 6 boost #'s. he also should not need methanol injection either, not yet.

rev, you do need to also get the timing under control for boost.maybe this could help. http://www.dalemfg.com/dale_018.htm . i know it is for corvairs, but you may be able to adapt it to a point type 6 cyl dist. tom

I know the AFR is lean hence the short burst. No IC yet. I am running Shells 93 Ocatne. I am going to wire up the timing retard feature of my MSD box also before any more testing to pull timing at WOT also but its hard to hear detonation with the chattering valvetrain, which is actually first on my list now.

RevOD,,,


Using an intercooler would help get intake temps down, thus reducing the chance of detonation, even @ 5 psi of boost pressure.

An intercooler will allow you to make more power even @ 5 psi.
What heat range spark plugs are you using?

Remember,,,, you cannot hear all detonation,meaning ,, your engine could be detonating & not hear it.

If you want to save money & not use high octane fuel(93),you could run 87 octane w/methanol injection.

Otherwise,, you could go up to 14 psi boost,(or there abouts) pressure w/methanol injection & 93 octane fuel.
You have the boost timing master MSD?

MBHD

No my digital 6 has a Nitrous timing retard, basically it will pull x degrees at the push of a button, were going to wire it up to a hobbs switch to activate it under boost.

I know an IC will help as stated before i have one just need to look into mounting it. As for plugs off hand i dont remember but I went 1 step colder then the stock plug.

I dont think I want to chance a 80,000 mile stock bottom end with 14psi... lol 8psi tops once we get the rest of the issues smoothed out and the IC installed.

Rev, Sorry I have not got with you to come by the shop but been very busy trying to get a car done, will get with you soon.
On your car I agree with Tom I think your turbo is going into surge that what the strange noises are and the loss of boost and inconstant preformance. The turbine is too small and spins the compressor so quick that the engine can not use the air and is backs up. you need a larger turbine not a/r but a larger wheel I hate to harp on this but even the 250 six is a large motor and needs a big turbine wheel. Also the lean mixture makes a lot more heat and adds to the problem. Just my thoughts Harry.