NA 3.1L=>head & camshaft questions. No shortcuts, max

[Daeron]

Good Luck, and thanks for the engine porn!

[Xnke]

Might want to deburr that intersection of the valve clearance pockets...looks kinda sharp and thin to me. How did your shop cut the valve reliefs? that crane valve-shaped tool is just wayy expensive for my tastes. I do belive a properly modified and carefully chosen set of forstner bits could do just as well...

 

My new pressure cast pistons are on there way now...at 27$ per piston, I didn't think it was a bad deal for a NA L28 that won't see over 220HP, and is running SU's. Hopefully i won't have to cut valve reliefs into them.

[zredbaron]

yeah, i had noticed that the machine shop had scratched the skirts. i wasn't very happy about that, but their reliefs were good, and some 00 steel wool did the trick.

 

well, i've got the block back, but it never goes as smoothly as you think it will, does it? perhaps when i'm a little more seasoned i won't be quite so excited (and therefore more patient) and tell myself hey, i got it all here. 2 weeks, not 2 days.

 

anyways, here are some more pics.

 

note the small amount of water at the bottom of the bag. draped in plastic and an oversize tarp, and water STILL found its way inside! damn hurricane...

 

 

gettin' ready to go in. and damn, can i say that i had one *hell* of a time mating the tranny and engine together far enough to get the tranny bolts threaded. whew. evidently i really suck at that part.

 

 

so close, yet so far...

 

 

really took my time wrapping the headers and customizing my spark plug wires. hah. they're thicker than my batter terminal cables btw. go figure.

 

 

in other news i spent an embarrassing amount of time on a project that i *thought* was a great idea. hah. so, i have been pulling vacuum off of two cylinders, and i thought hey, why not all six and share the load and stop messing up the mixture for those cyls? so i went to about 10 hardware specialty stores and finally ended up ordering some fittings (they would have looked really sharp i must say), brought my intake to a machine shop, and was ready to go. i went home tonight to take the carbs off of the manifold and... doh.

 

what i *thought* was structural support between the manifold runners was in fact *also* a hollow tube that connected all manifold runners. so basically, porting vacuum off of one cyl was drawing vacuum from all six after all.

 

man, i'm dumb. it *would* have been a good idea though, right?!?

[Careless]

gotta love those taylor wires

 

I'm going to agree with Xnke on the valve relief jut. I think they could be rounded out with a dremel tool slightly. that makes for a very small and sharp edge that can heat up quickly. Hopefully it's not going to do any harm. * crossing my fingers for you!*

[PalmettoZ]

ordered the sunbelt cam #2:

 

"micro polished rifle-drilled billet ground cast iron." whatever that means. lol.

 

.565" lift

326 deg intake, 315 deg exhaust

 

(from .520" lift, 290/275 in/ex)

 

with this aggressive of a cam, i was concerned about losing some low end torque, but jim was adamant that through experimenting with johnc's cams and one other customer's, the more cam they added, the more power they got and the wider and smoother the power band was. the other customer went with this cam. this cam would also give me 500 more rpm to work with.

 

the way i calculate it, with the difference in lift, reducing gasket thickness from 2mm to 1mm, and allowing a .08 clearance, i need to cut .170 into the pistons for exhaust and .155 for intake. (jim advised more clearance on the exhaust valve) sounds like a lot. has anyone cut this much?

 

cherry pickin and opening the engine this weekend. more updates to come.

 

Hey-

A rifle drilled (more commonly know as "gun drilling") hole is one in which a drill bit that has holes in the flutes of the bits is used. During the drilling process cutting oil is fed into the bit under high pressure which keeps the bit straight and allows for a very long bit to be used. Runout from this process is minimal and makes for a very accurate hole as well.

Scott

[zredbaron]

thanks for the info, palmettoz. and welcome to hybridz!

 

well, the car is 100% up and running. here are some more pics...

 

 

here's my makeshift heatshield. the other side of it is asbestos, which

supposedly has very impressive heat shield qualities. here's hoping i don't

get header cancer.

 

you can also see the steel tubing and fittings that i routed between my two

manifold vacuum draw points. the idea was to pull symmetrically from the

two points, even though all cyls are connected. worst case scenario, it doesn't

matter at all, but it looks better than just plugging one!

 

 

had a chance to clean up the carbs. they look almost new again.

(they're actually 10 years old with > 20,000 miles!)

 

after this part of the assembly, i broke in the cam and sync'd my carbs with

my flow meter. i of course just *had* to take it for a gentle spin around the

block, and man... i've never heard such a beautiful sound.

 

no, seriously. i'm considering taking off my air box and taking my hood

off permanently, and just racing around with screens on the air horns. the

beautiful sound went away when i put the air box and hood on...

 

 

i had a local machine shop weld on a new plate on my strut brace that i

could bolt up to my camber plates. they had to do some custom machine

shop magic so i could get my socket over the nut. they did a damn good

job, i'd say...

 

 

the final product from the driver's side.

 

 

and also from the passenger side.

 

 

i did some carb tuning and found some rather curious results. according to

my weber book, 36mm venturis are a tad small (should be 38-40), so my 40

dcoe's leave the engine a little under-carb'd.

 

in the end, the car wanted more gas and less air. 160 mains and 180 air

correctors. i know, it sounds crazy (40-50 above main is nominal starting

place for air correctors), but i *swear* the car liked it! and the a/f ratio

agreed. my guess is that the cam was sucking a lot more air than before,

and this crazy jet combo happened to feed the 'small' venturis better?

 

then again, no doubt the 'small' venturis are responsible for my incredible

torque snap / instantaneous throttle response.

 

still can't figure out the idle circuit though. the car has *always* just choked

if i ever suddenly floor it below 3000 rpm. anything below and i have to

feather the throttle. it's still torquey as hell... the smallest pedal touch jerks

the car forward, but still, i would think i could floor it. pump jet perhaps?

 

regardless, the results are promising so early on. it pulls hard up to

6500-7000 or so (i thought the power was going to last longer), but i also

didn't expect it to still have so much torque down low. very good autox

motor. looking forward to a dyno tune.

 

as for timing, i have it linearly raising up to about 32-33 deg or so according

to my timing control knob. does that sound about right for my setup?

 

all of this was tuned with my calibrated butt and wind-noise dyno. it's

guessing 254 rwhp. just a WAG. hey, i gotta throw out some kind of

prediction before i go to a real dyno! hah.

 

here's a very disappointing video of my autocross this past sunday, but at

least it's something. my dumbass only recorded one run, and i zoomed in

on my dash, so you really can't see the course very well. to top it all off,

there was a crosswind, so when the car is driving toward the water, all you

hear is wind. i'll get a better one eventually.

 

here it is:

http://www.youtube.com/watch?v=ElwuZNmNGf4

 

in other news, i've been reading a lot about fuel online. from what i read,

AvGas is a really bad idea in terms of automotive performance. yes, it

resists knock, and that's what the 100 octane is providing, but it's

engineered for a different purpose entirely. it's engineered to be run in high

compression engines that run at low rpm (~3000rpm) and *at altitude* (ie

very thin air). it isn't designed for high rpm (and therefore doesn't have a

very fast flame front propagation) and doesn't have the same energy

content (BTU or calories per gallon) as automotive fuel, more specifically

racing gas.

 

i've read a lot about mixing your own with pump gas, even from using your

own brew such as mixing with toluene (117 octane). although better than

avgas, it doesn't always mix linearly like other fuels. also, there's a recommended

limit total present in your brew (arguably around 40% of so-called aromatic

hydrocarbons such as toluene and xylene) when mixing. unfortunately

there's no way to know how much your pump gas has already, so you may

unknowingly create an octane lower than you've calculated. (that's why it

doesn't always mix linearly, because the fuel your using might have more

aromatic hydrocarbons than you know -- it reaches a point where adding

more doesn't improve as much).

 

the better octane references i found:

http://www.offroaders.com/tech/octane.htm

http://www.elektro.com/~audi/audi/toluene.html

http://www.idavette.net/hib/fuel/page2.htm

 

the bottom line is, again, you aren't going to out-engineer the engineers.

take the race gas for what it's worth. i may only need 95 octane to prevent

knocking. i *may* make more power with 100, but there's no way to tell

unless i experiment on a dyno with real, no BS race gas.

 

i really want to dial in my jetting and timing on the dyno, too, but it would

be prudent to wait until i use up the last of my avgas and move on to a

better fuel.

 

so, for the next topic in this very thorough thread, what have the racers out

there experimented with? what do our L6s like when running 12:1

compression via the 3.1 stroker?

[Daeron]

A suggestion:

 

I know a great number of people have been suddenly cropping up that magically know ALL ABOUT how gas stations and their supply and pricing work, so I hate to talk about stuff like this, but I DO have a good idea and have known for some time now. In MY town, all the gas comes into the port, regardless of ultimate branding, and goes into one of two tanks: 87 and 93 octane. (This is West Palm Beach, Florida, USA, about 50 miles north of Miami.)

 

Chevron tanks show up, they add the Techron ©, top off, and go to the Chevron stations; whatever additive package applies, similar stories play out for the other brands.

 

 

IF the market is the same or similar in your area, you MIGHT be able to find some hole in the wall or other privately owned gas station and get to know the owner to find out if you can find gas that you DO know all of these facts about. If you're going to the lab anyhow, may as well get all the data you can walk in with beforehand, right?

 

 

Just a thought; I read the update and figured I would throw it out there.

[zredbaron]

a reasonable idea.

 

i gave VP Racing Fuels a call, and spoke to their resident fuel selection expert.

 

he wants to see me run their Motorsport 109 unleaded fuel, which is highly oxygenated (and would likely help my under-carb'd issue). he basically guaranteed a 6-7% gain at the wheels from avgas.

 

quite a claim!

 

MOTORSPORT 109

Produces more power than any other unleaded fuel. Recommended for higher boost applications with CRs up to 11:1 or naturally aspirated engines up to 13:1. Excellent in crate engine applications. Fueled 2-time World Jet Ski Champion' date=' David Sellés.

 

• Color: Clear

• Motor Octane: 101

• R+M/2: 105

• Research Octane: 109

• Oxygenated: Yes

• Specific Gravity: .722 at 60° F

[/quote']

 

 

that octane number seems a tad high, though (105 r+m/2). i very much respect that this is his industry, but 12:1 isn't THAT high. or is it?

 

any experience? *ahem, calling a mr. john coffey*

[johnc]

Listen to the fuel expert. At 13.6 to 1 I was running 112 (r+m/2) leaded. The combustion chambers in our cars are not the best.

[zredbaron]

very good, will do! just wanted an affirmation from someone who knows our L6s.

 

thanks, john.

 

i'll report my findings, but that won't be for a while yet. still have a few gals of 100LL to burn through...

[JMortensen]

Any chance you can test that AVGas vs race gas theory? I'm not buying it.

[zredbaron]

i'm skeptical about the claim, too. i have no doubt that race gas will outperform the AvGas

(the race gas is oxygenated, and the flame front of the race gas moves faster --> more

complete burn), but a number like 6-7% sounds outlandish. i'd buy a claim of 10 hp. (then

again, 6% is about 15hp assuming a base of 250hp)

 

the thing that i'm banking on, is the driveablity factor. i'm willing to bet that avgas feels

sluggish by comparison, especially in the less than WOT positions.

 

as for testing it out, i couldn't just swap fuels and note the power difference. i mean, i suppose

i could, but it wouldn't be the test results we really want. the car will want bigger jets, no

doubt (oxygenation, plus the fuel expert said to run it on the richer side of the stoichiometric

range of my a/f ratio). it might even want a tad more advance. unfortunately a truly accurate

test would require me to truly dial in avgas on the dyno, then swap fuels, then dial in the race

gas on the dyno, all on the same day. that would be at least one extra hour of dyno time, and

at 100-150 an hour that just isn't quite worth it.

 

what i was planning on doing, was swapping to race gas and doing my butt dyno tune session

on the same day. it won't have numbers, but if it truly were 6-7% i would feel a *significant*

performance jump.

 

if it simply *ran better*, then the ~10hp + driveability factor theory would be more accurate.

 

unless you or anyone else has any ideas how this could be tested?

[JMortensen]

You're right. It would require a lot of optimization to get peak hp out of both fuels.

 

In my experience the AV Gas works just peachy and I didn't notice any real difference on the butt dyno between AV Gas, Trick 112 leaded cut with 92, unleaded race gas from the track mixed with 92, and 92 mixed with homebrewed octane booster. The exhaust sounded a little flat with the octane booster, but that was really about the only difference I could discern.

[josh817]

If you happen to try 40 venturis tell me. I flared up the weber thread with a thought but I haven't gone about trying it (that being, no venturi on a 40 dcoe). Tell me how it is if you go completely without them... >_< Because I'm poor. I do however like your ignition setup. I oogled it in your youtube vids along with the rev limiter feature. However I don't see myself spending a thousand or two or three or however much you spent on it all. :[

 

 

EDIT:

Oh god I just heard your sound clips... Whats your idle (JohnC noted 1500), and what is that popping noise when you rev it... Not the typical popping when you let off the throttle but when you're on the throttle. I'm only running a .495" cam but can't get lower than 1000RPM idle at the moment... Yours sounds like sex though. :] I have some more reading in this thread before I say much more so I don't look like a butthole. Lets not let anyone tell us our 3.1L motors aren't rev happy!

[Guest s30-260]

wow, there is a crazy amount of info to take in here, thanks to everyone who has thrown in there input, i just recently found this site tho i have been toying with z cars for a few years now, and not trying to crash this thread but i just read it from start to finish and i wanted to say thanks for the info you guys saved me from alot of trial and error. and zredbarron you have the cleanest/nicest looking engine bay i have seen and i love the ignition setup. and just adding my 2 cents i had a noticeable difference between VP fuel and AVgas, sorry no dyno numbers but better throttle response after tuning, much better. thanks again for all of the knowledge flyin around here!

[wondersparrow]

Well, I have to say, I am quite angry about this thread. I started reading it just after lunch and have got no work done at all today. Good thing the boss isn't looking over my shoulder But seriously this thread is an inspiration. I learned loads about the L series engines today. I have been looking into ways of improving my race engine as well as what I am going to be doing for the next. Thanks to everyone that brought their knowledge to the table.

[zredbaron]

i couldn't agree more! this thread has been the main source of direction for my engine, and i'm quite pleased with its evolution!

 

thanks again to all who contributed.

 

and by that i mean i now curse my 'tiny' tires...

 

update--

i finally purchased some of that vp race gas, and man... it makes more of a difference than i had hoped for. i am getting a dramatically more complete (and faster) burn, and it hasn't even been tuned! not at all! i couldn't lay down the power anywhere, which was frustrating, but yet satisfying at the same time. that is, after all, proof that all of the time and money put into my engine has paid off!

 

i plan on getting to a dyno sometime in december hopefully. i'll report the data when i've got it, but in the meantime, here's a video from today's race:

 

(note the watch in high quality link)

 

as you may or may not be able to make out, i'm having a hard time with the power, both in terms of keeping the rear end hooked up and taming the beast. i'm really, really having a hard time being smooth. manual steering is a whole lot more varsity now.

 

question for you racers out there... the pulsing of rpms that you hear when i'm under load in a turn and going over a bump (ie the tires beginning to break loose and me having to be ginger with it)... to me, i think its the result of perhaps not the stiffest suspension (225# springs over illuminas) combined with my quaiffe hunting for where to put the power.

 

in my case, is the quaiffe doing me more harm than good, or is this just the challenge of having more power than you can use?

 

(if in the case the answer isn't so simple, i'll shift this to a new thread)

 

thanks!

[JMortensen]

question for you racers out there... the pulsing of rpms that you hear when i'm under load in a turn and going over a bump (ie the tires beginning to break loose and me having to be ginger with it)... to me, i think its the result of perhaps not the stiffest suspension (225# springs over illuminas) combined with my quaiffe hunting for where to put the power.

 

in my case, is the quaiffe doing me more harm than good, or is this just the challenge of having more power than you can use?

If you're spinning the tires and have to back off, then the Quaife is hurting you. To what extent is hard to say. You can tune the suspension around the diff, but it is usually done with stiffer springs all around but stiffer in front, a smaller front bar, and no rear sway bar. I think if you tried to loosen the bar or delete the rear bar with the 225# springs you'll end up with excessive body roll. If you want the more technical version of suspension tuning, search "weight transfer worksheet".

 

There is also the matter of throttle control. There will come a point (sounds like you're there) at which you can't hit the apex and floor the throttle. You'll need to learn how to ease into it.

[zredbaron]

yeah, i was afraid of that. hopefully johnc will pipe in, too. i still intend to experiment with no rear sway... but that will have to wait till next season.

 

There will come a point (sounds like you're there) at which you can't hit the apex and floor the throttle. You'll need to learn how to ease into it.

 

uh... i couldn't floor it *anywhere.* in the turns, the tires were breaking loose at like 1/2" of pedal (or so it seemed with the adrenaline!). driving my Z now requires a level of finesse i don't yet have. it was all i could do to keep the car neutral in a turn and NOT break the tires loose. keep in mind this video was my best run, so this was the most finesse i was able to muster.

 

it might as well be 600hp or some other obscene number, because i feel like i cant use it.

 

(60 degree temps didnt help the traction dept, either)

 

if it sounds like i'm exaggerating, i don't blame you. that pedal was waaay too touchy today. i have no doubt the dyno will back up my claim.

 

how does that saying go? you reap what you sow... curses! my track times (relative to my competitors) are going down because its now so much more difficult to drive smoothly.

 

and by that i mean its soooo much more fun...

[zredbaron]

by the way, jon... although that fuel claim from the VP expert (gain of 6%) is untested by dyno numbers, i am here to say that it *feels* like more!

 

the reason is that this crazy fuel burns no matter what. my mixture is bad, my timing is a stab in the dark, but it burned faster and more complete than ever. i had power down low when it used to just bog until the cam kicked in.

 

so, my report is that this fuel really is all that.

 

however... the price is about $14 a gallon AND the mpg is worse because of density and oxygenation reasons. financially worth it? absolutely not.

 

but somehow its well worth it and i doubt i will look back. who knew?