TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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I've been lurking for quite awhile. I finally dove head first into my 2nd major buildup. Picked up a core for $200, everything is at the machine shop being mag'd, cleaned, ground, bore/hone. Now I'm waiting to get it all back. They have my pistons too to measure for honing.
So far -
block/crank - cleaning+machine work - $400
6" scat 4340 forged i-beam rods - $170 - bushed full floating
intake manifold runners ported, gasket matched, 2" bores - $100
(had it done at a perf head shop)
2" TB, ultimate tbi mods - already had
speed pro pistons h140cl+30 - $209 skinny rings, 2 1/16,1/8
AFPR - trying to get one or mod stock one
#68 injectors from TBcity - $131
crane cam - replaced the 266 don't know # - 210/216@.050, .440/.454 114ls - $103
heads - 14102183's - free, don't know if they're worth anything
if porting is not worthwhile, will pick try to squeeze AFR's into budget. compression will be 10:1 will iron heads, 9.8:1 with 64cc afr's.
Atleast assembly is free though. Still need rings, fuel pump, fuel lines, lifters, whole valve train, 1.6 rockers, high volume oil pump, fel pro master gasket kit and alot of tuning/chip work and other little stuff i bet. Need to get my hands on a set of shorty headers also. 6" rod 355 tbi, i like the sound of it
Last edited by z71stroker; 12-30-2004 at 10:47 PM.
One thing I dont like is the high CR. On a street engine with cast iron heads, thats going to be a recipie for detonation with a smallish cam. Probably 9.5:1 would be better to use on the street. IMO, a CR of around 10:1 isnt much use unless youve got a large cam with a tight LSA. I dont know if you can correct that with the parts your running or not. I suppose you could use larger chamber heads but then you give up the benifits of a tight combustion chamber. With aluminum heads, though, 9.8:1 or so probably wouldnt be that bad. AFRs may be too much for the two injectors to keep up with fuel wise. Maybe a slightly milder head?
I am leaning towards the world products sr torquers, the 67cc chambers will drop me to 9.6:1-ish. w/o aftermarket heads the "lowest" i can drop my compression is 10:1 w/o thicker head gaskets. and I think crane replaced that cam I had listed, PN is 113934, but it's listed as 212/218@.050, and .446/.459 114ls now, vs what I put up in the top post. Tuning should keep me out of idle hunting still though? its only 2 degrees?
You should be fine with those heads and cam. With tuning it should idle quite nicely. That cam doesnt have much overlap so itll pull good vacuum. Id also get the larger 80 pph injectors and a good fuel pump so you dont run short on gas like you will with a stock pump.
P.S. you could also run vortecs with that cam. Youd need a new intake but it would be an improvement over your current stock one. With that youd have a 350 HP longblock. Jon runs mid 13's with a similar setup.
vortecs it is. is around $300 the norm for the tbi vortec intake? btw, how do I post pictures? re-routing the EGR is pretty straight forward? I did a search and read the external egr post, he was running it off the d-side AIR, I don't have AIR. I'm not certain how to plumb it. Think I'll go look at my current set up and and print a picture from the top of the vortec intake and make some notes. Anyone want to throw P/N's out that I'll need, that will work? Or in my case, will it be easier to tune EGR out completely?
Last edited by z71stroker; 01-01-2005 at 06:19 PM.
I would advise against the 80pph injectors. Just my experience talking here; tuning the thing at low rpm's is a mo'fo with that much fuel dumping in there.
I really don't think idle tuning has much to do with the size of injector. It has alot more to do with cam size and air velocity at idle. I'm running 70 lb'ers at 22 psi which is the equivalent to 110 lb'ers and I'm not having much trouble on a 280-300 hp motor. My PW are around 1.2 to 1.5 ms. So I have room to shorten it further, around 1 ms is as low as you can go. 80 lb/hr injectors shouldn't be a problem on a mild 350. I could see where they would be tuff on a mostly stock 305.
Just bought a used set of assembled vortec for $300. They've been hot tanked, so I can't tell how used they are. They are casting 906, but I'm putting all new retrainers, springs, locks, valves in em.
Buy the larger injectors, youll want the additional fuel. You could also buy 65's and run them at higher pressures then the 80's, but the end result is still the same.
compression is going to be 9.8:1 with the vortecs. I think tuning EGR out will be easier for me. I don't have a visual or sniffer test in texas, they slam on the brakes, ask if you have a cat - you say yes of course, and then check blinkers, wipers, lights etc. How much of a difference is there between where the vortec manifolds connect to the Y-pipe and the 87-95? curious as to how much exhaust system modification will be needed. What kind of pressures am I looking at with the larger injectors? gonna need a 190lph walbro? will the stock fuel lines handle the extra pressure? thanks, i should have the motor back at the end of the week to start assembly.
oh yeah, this is the shop that I go for all my TBI/FI needs, they're a whole 5 min away, http://www.fuelinjection.com/
I have read several different ratings for stock springs, I understood them to handle up to .460-ish lift, I have read up to .420, .450, .470, I am putting in new springs, but if I have to machine them for springs to handle over .450 lift since I'm running up to .454 lift, that will kinda offset of the killer deal I got.
Shoulda just paid $450 for the pro-toplines with screw in studs and machined for .500 lift springs, ....hindsight bites. lol
:edit - fixed link
I need to go get a baseline dyno run too.
Last edited by z71stroker; 01-03-2005 at 05:38 AM.
I got to go pick up a crane 10309-1 spring/retainer kit for the heads tomorrow, cam/rings get here thursday. machine shop called me about the heads i got free - one was cracked around the exhaust seats on the 2 middle cylinders .... and they were 193's not 183's i read the # wrong. I need to assemble this thing and stop ordering parts, gettin expensive lol. still don't have the block/crank back.
this may be a dumb question but it kinda ties in??? well i want to know why on a gm 350 or 305 or whatever, 10.1-10.5 is a high cc and is easy to detonate? and i know of many imports that run on a 10.5 compresion even some of the domestics are having higher compression running on 93 or 92 octane, is it because they are usually 4 or 6 cylinders and draw in much less air?
if he uses 93 octane gas colder plugs and less advance why can't he run with a 10.1 compression? just asking?
Originally posted by sunset92 this may be a dumb question but it kinda ties in??? well i want to know why on a gm 350 or 305 or whatever, 10.1-10.5 is a high cc and is easy to detonate? and i know of many imports that run on a 10.5 compresion even some of the domestics are having higher compression running on 93 or 92 octane, is it because they are usually 4 or 6 cylinders and draw in much less air?
if he uses 93 octane gas colder plugs and less advance why can't he run with a 10.1 compression? just asking?
Motors with that kind of CR are running aluminum heads. Aluminum dissapates heat much faster than iron and in turn keeps the chambers cooler. Cooler chambers will allow for high CR's before detonation occurs. Iron heads are heat sinks and will not tollerate that type of CR without super high octane fuels.
i already knew that much... but i did not know if there was another reason? because i have seen alot of cars in the car craft mag and other mags that have cars running up to 13 or more on the compression ratio and i don't think they used aluminum heads, i am sure they used 108 octane or higher.
i have an old write up on aluminum heads vs iron and that was one of the benifits and it said they were easier to repair. plus they are lighter. so he would bennifit from going with alumin becasue of the weight reduction and increased compression.
It's just a general rule to match the compression to the cam, you can run more compression but you need to know what will work. A lot of guys run 13:1 and 14:1 compression with iron heads at the dirt tracks, but they get to run alcohol, alcohol laughs at 13:1 compression, they aren't restricted to 93 octane. they don't have to idle in traffic in summer heat with the a/c on with crappy pump gas with all its chemical additives either.
:edit
Last edited by z71stroker; 01-04-2005 at 11:44 PM.
I forgot to ask, how much massaging do 87-95 accessory brackets need to mount onto either tbi intake or a performer intake with the different vortec intake bolt pattern?
Originally posted by sunset92 this may be a dumb question but it kinda ties in??? well i want to know why on a gm 350 or 305 or whatever, 10.1-10.5 is a high cc and is easy to detonate? and i know of many imports that run on a 10.5 compresion even some of the domestics are having higher compression running on 93 or 92 octane, is it because they are usually 4 or 6 cylinders and draw in much less air?
if he uses 93 octane gas colder plugs and less advance why can't he run with a 10.1 compression? just asking?
Another thing is that w/ 4V/cyl., the CC is smaller and more compact then a CC on your average SBC. This means that teh mixture will burn more quickly, need less advance, and be less likely to detonate. One of the many advances incorperated into modern engines.
well you need to realize ,the gas we use today is so much more refined than the stuff from just a few years ago ,you can get away with using 10.0 to 1 CR and even more even with 89 you can run faily high CR's with out much problem long as your not running a 195 tstat and your tuned for the lower t stat,don't use a lower temp t stat with out tuning for it.
Anybody need to buy a set of l31 vortec heads? I bought a set of pro toplines from tri state heads for $599, plus I already had picked up these factory heads mag'd, hot tanked fully rebuilt factory castings for $305, they have a 1 year written warranty for any defects in the head or workmanship. I need to sell the factory castings so I can finish buying the last 3-4 pieces I need for the build.
$300 bucks plus whatever shipping is! I'm going to post this in a new topic also.
both sets of heads arrived today, the stock 906 vortecs I bought for $305 and the new in box pro toplines machined and clearanced for .550 lift, 120lb springs, 3/8 screw in studs and guide plates, they weigh 53lbs a piece, all i can say is beefy. and then I looked at my wallet and it's not quite so beefy anymore. block is .030 over, honed, new cam bearings, and I have it back, just waiting for the balancer, pistons, rings, rods, crank, flywheel to be balanced, I will pick them up monday and start putting the motor together, and I picked up a comp cam 268h from a buddy at mission machine for $35 brand new, I'm so tempted so stab it in, but I'm worried about my lack of tuning so far with that cam, so I have the 218@.050 .454 lift 110lsa, or the 212/218@.050 .446/.459 114lsa crane cam. I still need to get a vortec style intake and some roller non-rail rockers and an adjustable timing set. whew, can't wait to see this thing on the dyno. everything is going to be painted black or aluminum.
Originally posted by z71stroker I forgot to ask, how much massaging do 87-95 accessory brackets need to mount onto either tbi intake or a performer intake with the different vortec intake bolt pattern?
So far I've had no problems installing the accessory brackets on the engine. The problem I will have run into is when I remove the valve cover. (using 1.6 rr) So far I've had no problems installing the accessory brackets on the engine. The problem I will have run into is when I remove the valve cover. (Using 1.6 rr.) I will try to post a picture tomorrow.