Here is a 6.0L with dual plane intake vs LS1 intake and another of the 6.0L with a Trailblazer intake vs the LS1. Down in the 3,100 rpm range the dual plane is making around 25 ft/lbs more than the long runner truck intake and even more over the LS1 intake.

I did testing on a 305 back in the day the TPI only exceeded the dual plane TBI in a very narrow RPM range near peak torque.

 

Found my old post on the 94 G-Van L03 I had years ago. Stock TBI heads and cam with the cam retarded 4°. TBI vs TPI. TPI was running with a Vortec PCM and electronics.

 

Thanks image TOO small to read.

Rich

 

I edited it, did not notice it only saved the thumbail image.

That was a stock GM TBI manifold bored to 46mm with a 46mm TBI unit, an open center 1" spacer and a hypertech powerbowl under a modified stock air cleaner. May have had a 1/4" 454 injector pod spacer under the fuel meter assembly, I forget now.

 

Well thanks for trying.

Sadly your stuff is SO high Performance as to be comparing a Pinto to a Corvette...

 

I can't read the "6L vs. LS1" comparo, it's too small. But the dual plane with spacers etc vs. TPI looks virtually exactly like the L98 vs. LT1 graph. TPI makes it's expected mid range "bump" and then it's done. "Short runner" dual plane has a flat curve.

 

OK I am getting lost.

What I am seeing seems counter to all I have read.

And counter to what I have been able to get...your chart shows an Chevy 94 350 stock engine reving to 5900RPMs.

Every Stock Chevy 350 I have owned could not get over 5000.

You do say your retarded the cam so that might be how it did it.

So why did GM spend millions creating the TPI system??

And why did Ford follow suit and make one very much like it if the TBI was so great??

Why not just do what they did with the 76 Cadillac, a simple manifold with a throttle plate and port injectors??

Rich

 

305 not 350 and it was full bolt ons with a stock long block. Stock GM 178/194 cam retarded 4° with 1.6 rockers on it. It was done making power well before the fuel kill.

 

Exactly. Why? And it wasn't Ford that followed suit....everyone has. There is no magic in a dual plane intake.

 

Rich, putting everything we have learned over the years to the side in reference to how to fudge hexadecimal numbers, as well as aftermarket parts, when Tuned Port Injection was released, it did so with an all new Mass Air Flow system for the F-Body, though the Mass Air Flow system itself was not exactly new to GM. The quality of engine parts released by General Motors back then were anything but (meaning cast), and the overall size of the stock valves in conjunction with the factory cam specifications underlined how much power GM was shooting for, from a stock perspective. Injector size will usually dictate targeted factory peak horsepower, and in this case, 19 & 22 pounds respectively. GM was never interested in hearing how people could run this or that with cast parts, or make this much power with cast parts, their goal was sales and longevity....

So since cast parts ideally have a tolerance level of around four hundred horsepower, limiting air and fuel will bring it back down to where they needed be from a sales perspective, this is why the factory ECU was limited to 255 grams per second. Again, this is before we figured out how to fudge the numbers for the system to read more. There was simply no need for the engine to rev to the moon with what it was coming with, so they focused on where it would be making it's power, not to mention miles per gallon, etc.. Horsepower was nothing new to General Motors, so there was always a method to their madness. Back then the speed limits were lower, competition was slower, and buyers just wanted something that appealed to them for the time. Not to mention, GM spent millions on the ECM system, not Tuned Port Injection. The Cadillac you pointed out was an earlier attempt, but it was Speed Density based. They were having issues with that system, but eventually figured it out and returned to it years later....

- Rob

 

Fast355 is very particular about his fuel economy and has a shitload of tuning logs. Whatever he says his engine behaves like is probably true. Whether theories are right or wrong, the data just is what it is.

 

I am a big car fan. I watch as much as I can on new and old cars.

IF I had tons of money and wanted a very fast car I will get a Tesla S. They beat full blown Dragsters. For City driving they cannot be beat.

As I don’t have much money the second best car in my book is the 03/04 Crown Vic P71 as both a snappy good handling car that thanks to so many made and ease of both repairs and part supplies both used and new.

For highway cruising and long trips I cannot find anything to match or beat my Van.

The ONLY flaws of both cars are poor MPG.

I plan on helping both of these cars get better.

The only thing holding me back on the car was trying to come up with a system I could share, I have set that aside and will just making my personal cars get the best MPG.

The van has needed a new motor for two years and that build has been what we have been talking about in this thread.

I have watched the trend of cars and engine go from what I believed was a good MPG engines to higher and higher performance higher HP, with NO improvement in MPG. That has stayed at a MAX in any performance car at 30MPG.

Overseas cars do better in MPG, as found out here in the 90s when we learned Camaros down under were getting 30/35MPG where our cars got 20/25MPG.

I am fairly sure anyone whom has considered these facts knows the FIX is in.

I have been trying to find a way to unfix our cars. It is NOT easy. Lean Cruse seems to be a good beginning, which is why I bought three complete TPI Systems.

For the van I felt a bigger motor was part of the cure, and one built as low RPM engine that could make power with the lightest used of fuel possible, and what I have seen with a number of cars running under 2000s seems to make the most MPG. BUT these cars gearing limits that RPM range to low MPH. One thing I am planing on is adding a second OD to add extra low gearing to allow that RPM range at higher high way speeds.

I really think the TPI is part of this idea. It was made to work at lower RPMs than any of the newer engines that are now made to run higher RPMs and to make MAX HP vs. Torque.

BUT I have learned the TPI is centered around 2800RPMs so was looking into seeing if this could be shifted lower, like advancing a cam can.

As I have run out of time here in hot AZ I am forced to put this new engine directly into the van using the stock fuel system to get her running THIS summer, and to brake in the new engine before trying to figure out a new intake and PCM which I now plan on doing come winter, some 6 months away.

SO if I can make the TBI system better I am interested in how.

I have heard a better carb high rise dual plan manifold MIGHT be a better system.

So I am asking about that idea, and why this long post, so you can see what I am aiming for.

Rich

 

That is where you are wrong. Multiple articles and thousands of hours of research and develpment shows otherwise. ANY intake manifold has a resonant frequency. Because dual planes have multiple runner lengths in the same manifold it has different resonance RPMs for each cylinder. That is the reason it delivers a very flat, broad torque curve. Air has mass and moves through the ports at high velocity. That causes pressure waves within the manifold as the valves open and close. That pressure wave bounces off the closed valve and back into the plenum toward other valves that will be open. That pressure wave helps carry air through the open valve. Not sure why you cannot do a little research and stop putting out bad information. After 90 or so years of dual plane development they absolutely have a science behind why the work so well at what they do. They worked well and even Mercruiser saw a benifit to keeping the dual plane design and adding port fuel injection to it. A dual plane manifold will always have a broader torque curve than a tuned length manifold.

 

Here is a whole article explaining dual plane intake tuning. PFI fixes the fuel dropout problems related to a dual plane manifold helping equalize the air/fuel ratio between cylinders. 4.3 TBIs used staggered sized injectors in many applications from GM to help with the mixture distribution.

https://hotrodenginetech.com/how-to-...uction-system/

 

OK So will swapping in a high rise dual plan intake (with no fancy work on it or the injection system) Help my van??

And if so suggestions as to make and model that will be best. Plus I still plan on running the TBI injection system.

Swapping to a like manifold with port injections is something i might consider later.

Rich

 

I have nothing but praise on the Edelbrock EPS or Performer RPM for Vortec heads.

I would suggest a fuel pump change, more fuel pressure and tuning though to run a Vortec head 383.

 

Thanks.

Rich

 

Who's providing bad information here? :bigears Fast, I know that "any runner" has a resonant frequency. That is stating the obvious, but thanks. LT1 runners have a resonant frequency; it's something like 8000 RPM for the 3rd harmonic. NOTE, that what I actually said was:
Mercruiser used a dual plane because it was CHEAP, and met their criteria. It boggles my mind that with all your "expertise", you throw down that someone used a budget intake on a budget engine...."so the must be awesome!". Strong work there. Show us a Mercruiser from today, that's running a dual plane intake please. You won't find one. Why not? Oddly enough, Mercury moved on to something better; a LTR intake.

"Power and acceleration is delivered with 6.2 liters of displacement and a long-runner scroll intake manifold that optimizes air flow for higher torque."


...Huh.


The OP claims that he wants to maximize tq at 1800 RPM. How is a short runner intake, that inhales through 1/2 a TB and makes 8 different power peaks (spreads the tq curve w/"different length runner") going to accomplish that? How is it going to accomplish that better than a SLTR intake? It won't.

 

You yourself said there was no magic to a dual plane. Reality is he will never run at one specific RPM at cruising speed. What he should be optimizing for is torque from about stall speed up to about 3,000 rpm. That will provide the best overall fuel economy for ALL sane driving conditions. Dual plane intake and tri-Y headers with a merge Y pipe will provide the best overall torque curve on the low rpm side of things. My best MPG in my old G20 van came from a 10:1 305 with worked TPI heads, a stock 300hp 350 camshaft, performer rpm intake, big block TBI unit and thorley tri-y headers. Running super lean with a MSD 6a ignition box and the hottest intake air I could provide to it. I ran 2.8L injectors at about 30 psi.

Obviously a variable intake runner will perform better. That intake probably cost more than his whole engine build. Not to mention that is probably a direct injected 6.2 LT engine.

 

you are right. I did say that there is no magic in a dual-plane. And there isn't. Where are the current Mercury Marine engines with dual planes? I didn't see that in your post.....

 

Hope the OP doesn't mind, but my interest was peaked in this MerCruiser "long-runner scroll intake manifold". The dang thing looks a lot like the old Crossfire intake (on the right), but with improvements. That said, wouldn't mind trying it out on a 383 Vortec streeter.

 

That is the standard L31 base. I doubt it is the base used on the dual scroll. The dual scroll does not look to have external injectors. Becase of that fact it looks like the dual scroll is based off the latest GM 6.2L with direct injection.

 

As I mentioned they don't even use a Gen1 any longer for that. Looks to be a GenV LT based 6.2L. They have marched on with a much more high tech engine. I know Indmar used the SOHC Ford 6.2 while Ford made it and got away from GM.

For the OP it would be hard to beat the fuel mileage of a 4.3 V6 LT engine. They come in the newest Express/Savanna vans and some pickups. Direct injection, Variable cam timing, Displacement on Demand and an 8 speed trans behind kt. The 2.8L Turbo diesel and 2.7L Turbo 4 cylinder gas engines would also work extremely well in the MPG department.

 

Exactly. And they moved on from "dual plane" intakes too. Why?


IDK what engine they're using. Their marketing says that they have the flexibility to "lower friction" with proprietary design, since they're designing/building their own engines. Maybe they are, but the exhaust manifold appears to be a Gen I looking, EIIEEIIE arraignment. There is so much plastic, plumbing and wiring on the engine that you can't tell WTF it is. Damper flange and water pump also look like Gen I Chev, and the bore/strok is spot on, for a virgin bore, "383".

Whatever they're using for a long block, you could probably get or make a dual plane for it, right? Right. But what are they using? Earlier you were touting, (condescendingly) the virtues of the Dual plane for low end (the OP's 1800 RPM) tq. You told me to do some research....while knowing nothing of my profession or experience(!). Then you whipped out Mercury, to try to slam dunk the point that dual planes are great. Say....WHAT!? In reality, Merc used dual planes years, if not decades ago, and they did so as a CHEAP/easy foray into MPFI; not b/c it made for a low RPM TORK monster. SO....knowing that (in spite of my "lack of research"), I tried to make that point, by asking you to show us a current Merc with a dual plane intake. Of course you can't, because they don't offer any engines with that intake system; they've moved onto a better, more effective intake system; an LTR MPFI system. So recommending a dual plane to the OP for his "1800 RPM peak tork" engine....that is the essence of "giving bad advice".

 

THIS would be your quickest way to significant fuel economy improvement: ship your van to Australia. They use British Imperial Gallons; 10 AU gallons == 12 US gallons. Instant 20% increase in MPG! (They also have more consistent and slightly higher octane gas, which makes more aggressive factory tuning safe/possible.)

You need to run a DCR calculator on your proposed engine or you’ll end up needing to run race gas in the thing... It’ll increase your MPG, but make you broke.

Engine coatings are also a HORRIBLE value for your goals; leave that off.

Consider a small tri-y exhaust to help your mpg goals, too or at least like 1.5” primary long tube headers.

If you’re trying to get max mpg and torque out of pump gas, you can push things on the DCR if you keep temps down, but IAT is most important: cold air intake and probably a good water or water meth injection setup (just use winter washer fluid) -inject at high load.

If you’re actually going to spend a lot of time under low load highway cruising (van at highway speed still takes a lot of hp to push down the road, so I’m curios whether lots of low load cruising is actually going to be a thing) that lean burn tuning is very important: but leaner mixtures are harder to burn so you begin to need a better and better ignition system and larger spark gaps to light the fire as you burn leaner and leaner. True Plasma ignition can light off VERY lean mixtures AND makes a faster combustion event that requires less ignition timing which itself increases torque a bit, but true plasma ignition is insanely rough on pretty much all spark plugs. -I fear sending you down the plasma ignition rabbit hole as you seem to latch upon small details and over index on them (I can recognize it because I tend to do the same; ADHD hyper focus...) but it’s a useful extreme example to show how ignition and spark gap help get the leanest lean burn.



Adam

 

Rich, I hope you didn’t buy the Rhodes lifters yet; another waste of money that may cause more problems than there’re worth. The Rhodes lifters are a crutch for people who bought too big of a cam in the first place and want to throw bad money after good / not admit to themselves that they bought too big a cam. You’re going into this already buying the RIGHT cam; all these lifters will do is burn money and make your cam events unknowable. -Fine, you CAN in limited situations use Rhoads lifters to make a bigger cam act smaller at low rpm but they’re not Panacea and WILL limit rpm capability from them bleeding down; this is my disclaimer for the Rhoads apologists...

How are you supposed to predict your DCR/ cylinder pressures to avoid detonation on pump gas if you don’t even know what the seat to seat duration is when using those lifters? You don’t want random and unknowable seat to seat duration valve events with what you’re doing: 9.0 or 9.5:1 static CR iron? Heads, baby cams, lots of Cam advance And then throw unknowable valve events in the mix: that’s a lab device for illustrating detonation to people, not a commercial vehicle engine.

If you making a living depends upon this vehicle and it’s engine you should kill the science experiment engine plan, or you’ll kill the science experiment engine.

I can admit I love the science experiments as much as anyone, but you gotta rein in the scope if you want a decent chance at success, unless max learning is what success looks like and you’re willing to pay the steep “education fees”.



Adam

 

I have run Rhoads lifters in two engines. Dodge Vipers had them from the factory. Its more than a crutch. It can allow you to run more cam for more power while still having tame driveability. I don't know who told you they lose high rpm power. In literally every dyno test I have seen the high rpm power is basically unchanged and in many cases above peak is improved by eliminating hydraulic lifter pump up near redline.

 

How do Rhodes lifters work? They have a high bleed-down rate and a large amount of travel (a lot of oil volume in the plunger) -they allow the oil in the plunger to escape at a faster than typical rate at low RPM when oil pressure and flow is less. Then as you get into the mid RPM ranges the pressure and flow in is enough to fully pump up the lifter, the problem is that as you apply more pressure to the lifter and you have less time to fill them with oil you end up having oil leaving the lifter body at a faster rate than it's entering it and they bleed down again.

Look at modern higher-RPM capable hydraulic lifter designs they're the exact OPPOSITE of a Rhodes lifter-> they are short travel and with a low bleed-down rate. This makes them "hang on" longer at high RPM or with higher spring rates and more aggressive loads before they start bleeding down. -This is the approach taken by Johnson Short Travel lifters, Lunati Platinum (I think that's their high rpm low-bleed down brand name), Mike Jones' hyd roller lifters, whoever CompCams is contracting with to make their "Short Travel" hyd lifters this week, and the modern LS lifters.

High bleed down rates is what makes the Rhodes lifters work and by definition, they'll limit the point at which they bleed down at high RPM.



-In examples where your cam isn't already running at the bleeding edge of your Dynamic Compression Ratio aka Cylinder Pressure / Combustion Temperature of your fuel, where you've choosen more HP in the HP vs. Torque trade-off you can use a high bleed-down rate lifter, like a Rhodes lifter to give you more torque / DCR / cylinder pressure / combustion temperature down low, BUT when you're starting from a baby towing cam where you're already at the knock limit for your fuel, all your Rhodes lifters do is move you into detonation / beyond your fuel limit, which is the scenario that the OP is facing. If you have no limit on what fuel octane you're going to run, you can run race gas or an ethanol blend and make more torque, but if the OP is looking to run pump gas and is already picking a compression ratio and cam duration that puts him on the bleeding edge; lifters like this just push you over the edge. He doesn't need them as he can just buy a cam that puts him on the DCR limit for his fuel in the first place and he doesn't need nor want the extra HP potential of going with a bigger cam and rhodes lifters.

The Viper didn't use Rhodes lifters; it used an alternative high bleed down rate lifter called a "Nola" lifter; same ideal though, sure.


Given the OP's Torque goals and narrow RPM goals for his power band a tighter LSA cam may also make sense. -> he's looking at tiny baby cams so overlap probably isn't a significant factor but a high speed exhaust (small diameter primaries) helps to prop up torque as overlap goes up, too as it helps prevent reversion which is a torque reduction.



Adam

 

Rich, the more I read on what you have planned the more concerned I am about this being a 100 Octane requirement build right about now.
Go fill out your proposed engine details on the Jeep DCR site and figure out your DCR with this cam and your proposed combo.https://www.jeepstrokers.com/forum/calculator/

Not only the small durations, but the wide LSA, hot Arizona air, high static compression and I'm guessing you're WAY beyond the limits of 93 octane pump gas.

You want all the cooling you can get. If you're going to go through with this. Piston oilers squirting the under side of pistons and an oil cooler is magical for reducing combustion temps and keeping detonation at bay in high rpm race engines and might help here; David Vizard has a quote that every 7 or 8 degree drop in IATs is the equivalent of 0.5 degrees of Octane worth of detonation resistance.

-Getting a VERY tight squish so you get a good quench action is magical free "octane equivalent" and you want this in your build for SURE. Cold Air intake is a no-brainer for this build.
If you can get a modern control system and do water injection or water /meth under load with the minimum quantity of water injected, I think that's the best way to avoid detonation on pump gas with the crazy DCRs you're proposing. I know it's not common in N/A applications but it's appropriate for what you're proposing here: high cylinder pressures to improve MPG and torque but with pump gas and in a vehicle that IS going to be heavily loaded and in a very hot climate.


Adam

 

If he runs 9.5:1 with the Rhoads lifters it will still be less dynamic compression than GM used on the 5.7 B/D car TBI 350s. Those had flat top pistons, 9.6:1 advertised and 178/194 @ 0.050 cam on a 109 LSA and 106 ICL.

My old cam was 218/228 @ 0.050, 110 LSA and 106 ICL. Rhoads lifters. 11:1 compression at 0.041" quench with aluminum heads. Ran very well on 87 octane not towing and 91+ towing.

My V6 and V8 Nissan/Infiniti engines have all had a very high DCR with the intake cams fully advanced. In the 9-10:1 DCR range.

Wide LSA lowers DCA for what it is worth.

 

We know that the OP want's to use a tuned intake, right? The TBI isn't tuned (to any RPM in the B/D car's operating range) but the OP wants one tuned to 1800 RPM. What do you suppose happens to DCR/cylinder pressure at or near the tuned intake frequency?

My old cam....
My V6 and V8 Nissan/Infiniti engines.... [/QUOTE]Oh dear lord. More anecdotal, not comparable, "story time". :ack: We know that jap-wagons have totally different combustion chambers....right?

 

Oh dear lord. More anecdotal, not comparable, "story time". :ack: We know that jap-wagons have totally different combustion chambers....right?[/QUOTE]

Just in case you did not notice...No room to get an intake with runners tuned to that rpm under the dog house. Best he could hope for is about 6 psi with a belt driven intake. It would be cheaper and more effective to boost it than it would be to build some one off manifold.

I went with a bigger cam because I wanted more power than the one I had ground for my out of the box aluminum heads and a stock 9.6:1 350 bottom end.

 

This is brutal. "Just in case you didn't notice", let's go back to post #65, where this was already covered...

Or maybe the runners go up and over the VC's, then curve something like the TPI runners and run back to the TPI plenum? If it was important enough to someone....I'm pretty sure they could figure out how to package it. There is room. Worth it? Not to me, but it IS possible.

 

The tight lsa of that cam helps but I’m not sure why you keep quoting the 0.050” numbers; it’s the seat to seat / adv #s that determine DCR. The OP is proposing a roller cam which will bring less seat to seat and adv duration for a given 0.050” duration which makes the chances for detonation WORSE and the DCR higher.

DCR is also only a VERY rough approximation of actual cylinder pressure / temp and the long runner intake will also make the actual cylinder pressures worse around the torque peak rpm.

again this build has everything going against it on the detonation front.

How much do the Rhodes lifters reduce the seat to seat duration exactly? Again, unknowable.


Adam

 

EXACTLY. I have a copy of Pipemax and can model the estimated cylinder pressure and required octane. It won’t take into account quench, or air, coolant, or oil temps but it WILL take into account the DCR, LSA, and wave tuning effects.

I think it’s going to be bad without even considering the Rhodes lifters...

 

I’m not sure what DCA is here; if you mean DCR, LSA technically doesn’t impact DCR at all because it’s only looking at static compression and the intake close event. If you alter LSA but keep the intake duration and Intake Centerline the same DCR doesn’t change at all.

Now LSA DOES impact actual cylinder pressure / likelihood of detonation, but the opposite of what you said. Tighter LSA decreases cylinder pressure.

 

Tighter LSA gives more cylinder pressure because to get the tighter LSA the intake lobe is ground more advanced. Most of the time the exhaust centerline is not altered alone.

https://www.compcams.com/cam-timing-...paration-angle