Chevy & GMC Vans

Thanks Gary

Jim

Jim-I honestly don't mean to offend bud.All I am saying is to complete one of this swaps/mods for most,it is a major life style commitment change doing without.That's all I am saying.

No Offense taken Gary

Just weighin all the facts in my mind

Take Care, Jim

My friend from another site is still playing with the numbers on the computer dyno:

Still playin' around with this tow motor....
Custom cam 206/214, 106/113/109.5, 0.420"/0.420, (-3)(29)(40)(-6) installed straight up.
Streetmaster intake manifold (1st design).
http://cgi.ebay.com/ebaymotors/Edelb...Q5fAccessories
RPM HP TQ
1000 88 461
1500 149 521
2000 204 535
2500 247 520
3000 289 506
3500 319 478
4000 346 455
4500 357 417
5000 348 366
5500 319 305
Peak BMEP 210.8 @2000. This is some serious cylinder pressure, so a very tight squish (I would be thinkin' 0.035" to 0.040" with a D-cup piston) would be mandatory to prevent detonation on pump gas

Mr_Roboto,did you see my request for a refresher on a TBI 600 cfm for this 383.Last XP I had and lost I think had all the ref material on it.

Thanks.

My ultimate question is with the RPM you're turning are 180s really essential for the operation of this engine especially with the HP you're producing. I'd try a set of stock L31 heads in the sim and see how things work out. You may be surprised it may cost you very little to no power for the $ you save especially with the valve lift you're at. You could run a set of stockers with no valve work meaning they would cost you minimal $.

Personally if I had a 383 to feed I'd cam up a bit, With exception to having more overlap (and probably more aggressive ramps) that cam specs out fairly close to something stock.

Why not a more modern intake like a Performer RPM? With a 383 and some heads like that you'll definitely be able to feed it. I've heard not to use the airgap one with TBI because of atomization but don't know how true that is. Besides that are you talking about the "Ultimate TBI mods?" Or perhaps a Holley TBI unit?

Just throwing some food for thought out there, back when I still had Engine Analyzer I would drop dozens of combos into just to see what would happen.

I have planed for a TBI all along for this project.Which one without spending thousands has been the real question.

Two nagging questions keep popping up.

First being told for a toy project they are fine.But they are very sensitive requiring constant programing for day to day changes.

Second the MAP to mas air flow sensor or the other way around is needed for it to work correctly.

All the numbers shown on this 383 low rpm torque'er are based off a 600cfm.

Find someone to cut you a chip. No one makes a production MAF system for the TBI vans, I believe EBL is out there but it would still need some calibration. It shouldn't take too much work and would give you OEM quality driving too.

Mr_Roboto- I looked up your ref:

http://www.dynamicefi.com/

Honestly I just learning about this.I am determined not to run a carb.

Google for the Mega Manual which is the Megasquirt EFI stuff. They go through a lot of the whys as well as the hows of tuning. There's a guy by the name of Matt Cramer who wrote a book on EFI system basics. There is also the DIY-EFI group and Thirdgen.org has sections for both PROM tuning (cutting your own bin) as well as for aftermarket systems like DFI or Megasquirt. JMO on this to use a system like the Megasquirt and be successful at it you need about 500 bucks now (was about 450 when I did it last) because you will need at least the box and I'd recommend a Wide Band. One of the cool extras I got that was about 40-50 bucks including some extra parts is a board that lets you mount your Megasquirt in a stock box case and use things like the TCC lockup and even the knock sensing system.

ED:

For a TBI system http://www.tunerpro.net/features.htm is an option you can use too. The hardware is probably in the 250-300 range, I would advise a heated O2 as the MINIMAL and would prefer something else wide band to datalog.

There is a guy that makes custom chips for TBI I had one made a few years ago, I will search through my papers this weekend and find it for you. Mark

Thanks guys very much.I will research the info provided.I need all the support I can get.One thing I kind of remember reading is the 383's are not very accepting to knock sensors and something has to be done about that.What I want to be sure of is the TBI doesn't limit the torque band without going broke to get that done.The donor van has a TBI with 65lb injectors lifted if that helps at all.I don't know why,but it seems the cfm's on TBI's are so big to make them work over a carb's cfm.I very much like the idea of a four barrel TBI like the one on the 454's.But I thought that was in the range of 900cfm and seems huge for the torquer style engine I am building.Same with intake manifolds.Don't want to disrupt all the planing we put into a engine with a broad torque band coming in almost off idle and with a peak in the mid 3's and having a rpm range of only 4,400.I wish the rpm range was higher,but it is considering the roller lifters,the needs of torque for towing,and me a stop light racer at best almost never buzzing this engine.The hp is going to be only 350'ish.

BTW-we found a error in the calculations I make in static compression ratio and adjusted the planning for the build.We will set the deck height at 10 down(not 0) and are forced to use the World S/R torquer 170cc 67cc combustion chamber heads.Really it is a blessing in that we wanted the lower intake runner size anyways.That will put us with 18 pistons at about 9.2 c/r.I could run it at 0 deck which is still below 9.5 c/r(really more towards the lower end of 9.4 c/r),but do have some concerns that the computer on today's gas would be pulling timing out and it would run(for the lack of a better term)like crap.I could still run the RHS heads at 72 cc's and that would land me at 8.9 ish in the c/r.Cam choices become more critical and I just don't like the idea of building a 8.9 engine.So the fix of that would to be to cut the RHS heads to get back to the 9.2 c/r range.That doesn't set well with me either.The idea of buying a new set of heads and have to cut them bothers me some.Still the RHS heads do have the "Clean Cast Tech" that I am sold on.But if they don't work for my application,then they just don't.

Well never the less guys,please do keep coming with the suggestions about the TBI and supporting computer hardware.I just want to develop a game plan for that now so when I am ready I'm good to go to implement that.

Thanks again for all the help.

1Gary wrote:Thanks guys very much.I will research the info provided.I need all the support I can get.One thing I kind of remember reading is the 383's are not very accepting to knock sensors and something has to be done about that.What I want to be sure of is the TBI doesn't limit the torque band without going broke to get that done.The donor van has a TBI with 65lb injectors lifted if that helps at all.I don't know why,but it seems the cfm's on TBI's are so big to make them work over a carb's cfm.I very much like the idea of a four barrel TBI like the one on the 454's.But I thought that was in the range of 900cfm and seems huge for the torquer style engine I am building.Same with intake manifolds.Don't want to disrupt all the planing we put into a engine with a broad torque band coming in almost off idle and with a peak in the mid 3's and having a rpm range of only 4,400.I wish the rpm range was higher,but it is considering the roller lifters,the needs of torque for towing,and me a stop light racer at best almost never buzzing this engine.The hp is going to be only 350'ish.

BTW-we found a error in the calculations I make in static compression ratio and adjusted the planning for the build.We will set the deck height at 10 down(not 0) and are forced to use the World S/R torquer 170cc 67cc combustion chamber heads.Really it is a blessing in that we wanted the lower intake runner size anyways.That will put us with 18 pistons at about 9.2 c/r.I could run it at 0 deck which is still below 9.5 c/r(really more towards the lower end of 9.4 c/r),but do have some concerns that the computer on today's gas would be pulling timing out and it would run(for the lack of a better term)like crap.I could still run the RHS heads at 72 cc's and that would land me at 8.9 ish in the c/r.Cam choices become more critical and I just don't like the idea of building a 8.9 engine.So the fix of that would to be to cut the RHS heads to get back to the 9.2 c/r range.That doesn't set well with me either.The idea of buying a new set of heads and have to cut them bothers me some.Still the RHS heads do have the "Clean Cast Tech" that I am sold on.But if they don't work for my application,then they just don't.

Well never the less guys,please do keep coming with the suggestions about the TBI and supporting computer hardware.I just want to develop a game plan for that now so when I am ready I'm good to go to implement that.

Thanks again for all the help.

Stock Camaros run 9.5, as do some of the stocker TBI engines. The HD engines tend to run a lower SCR however. Check your spec books on that one.

Besides that what HG are you thinking about? That could make a difference of a few tenths as well.

In regards to the knock system they are resonant devices. Different stroke means different frequency vibration to pick up on. If anything I'd think it wouldn't work as well rather than be overly sensitive. You can change the rate of knock attack as well as how quickly it recovers timing in the stock ECUs. A modified one will usually pull less timing when knock happens per incident as well as put the timing back in quicker.

The head gasket compressed is .040.The stock C/R we are saying has some timing being pulled is what we are thinking.We are thinking given a additional 38 C.I. it would be multiplied in the effect.

From what I think I remember,that the stock modified TBI's are limited with 350's to 400hp.That given it being a 383 needing more it is hard to tune.We are building really a peanut 383 on purpose for the sake of a torque'er engine.I am guessing I need high volume to build torque and follow along with the torque band.I don't know<please excuse I that I haven't gotten to read the suggested links yet>,but I sure like programs that learn a tune as you drive.I think I know that all do to some degree do that.Still that feature sure looks great to me and I don't know if I could get that without going broke.

From what I have seen of the Fast Systems,to me it seems the entry costs is low,but by the time you finish building it,it nickel/dimes you close to the systems already built.Am I wrong in this judgement??.

Part of it is probably also that the EFI will compensate better for engine variances as well as inconsistent fuel than the standard "dumb" distributor ever could and allows more precise control as well. Since you can do a timing curve that's a lot less linear it allows you to precisely adjust timing for your needs. EGR, cam profile, and things like that probably also play a role as well. What's interesting to me is that the cam overlap on most OE cams is very wide with low duration which means high low RPM cylinder pressures which could lead to detonation especially with higher CRs. I think that is part of where the EGR comes into play.

.040 is a rather thick HG, I think the last ones I used were .034 and even then a stocker is in the mid 20 thousandths. I'd also be paranoid about 0 decking, but that's just me. I like the idea of leaving a bit of meat in my block "just in case." Ideal quench is between 30 and 60 thou I believe according to theory so you wouldn't be in terrible shape to leave 10 or 20 on the deck IMO.

I have heard this and read it before on cam profiles for EFI's:


Fuel Injection Engine Camshafts:

For a camshaft to work in a fuel injected application, it needs to make a good vacuum signal.
To create a vacuum signal, that stands a reasonable chance at working in an application without having to re-flash the ECM computer, a camshaft needs to be:

a) Short Duration : 220-222 Degrees @ .050” Maximum

b) Wide Lobe Separation/Centers: 112 to 114 degrees Minimum
Do not attempt to install a camshaft with a 108 lobe separation in a fuel injected engine, unless you are planning to re-program the ECM computer.

There are camshafts that are ground to work within the stock ECM computer parameters. Usually these camshafts have 208/208 degrees duration @.050” (intake/exhaust) and 112 degrees of lobe separation, or 208/214 duration with a 114 L/C

Both of these camshafts would be designed to function in stock CID engines/stock compression and stock computer programming.

However, if the cubic inches of the engine or compression ratio is larger than stock, the camshaft grind needs to grow accordingly and a custom camshaft would be in order.
Also, having the computer re-programmed/re-flashed is recommended with any camshaft change, even the “no hassle/safe” type grinds.

While the camshaft may work with the stock fuel/timing curve programmed into the ECM unit, it will not be working at its optimum level…..Think of it along the lines of taking a performance carburetor out of the box, bolting it onto the engine, hooking up the fuel lines and running it. It may run but without tuning/jetting the carburetor to the engine, it will not work to its full potential.

While we are on this subject, there are some engines that you need to be wary of:

Late 80’s-Early 90’s 350 Chevrolets with a K engine code and an idle speed of 500 R.P.M. (TBI)
Early Ford V-8’s with the Speed Density fuel injection.
Dodge Magnum V-8’s
Any Fuel Injected application where the customer wants a loud/radical idle.


These engines/computer combinations have very special camshaft grind requirements, so should you run into one of these combinations, it would be best to call the Erson Tech Line (775/246-4062) for a recommendation.






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