turbo 200 build

aluminum head is still an option One more bit of info, at 2000 rpm in 5th cruising about 60 mph the turbo is making 4psi of boost. Shift into 4th at the same speed the turbo goes to 0 boost and my mileage goes up. I'm assuming the turbo is compensating for the cam at lower rpm?

when you shift into 4th at 60 mph the rpm goes up and the cam is making more torque at that rpm and doesn't need boost to maintain 60 mph.
So yes the turbo is compensating for the lack of power at low rpm.
The fuel mileage increased because at higher rpm the large overlap period has less time to throw intake fuel mixture out the exhaust.

One last thing:
Another reason there is no low rpm torque is the DCR is only 5.6 with this camshaft when it should be closer to 7:1
The 8:1 static compression ratio was designed for a small duration, high torque cam profile so going with a smaller cam rather than a larger turbo is the better direction.

If you were to go with a larger turbocharger you would need more exhaust duration to get power at the higher rpm making a single pattern cam profile better suited especially considering the long tube header you designed that offers scavenging.
So again the present cam is less than ideal.

You asked about E85.
It would allow higher boost than pump gas.
If you are already at a comfortable boost limit then there would be no advantage.

If you were building another dedicated E85 engine the compression ratio could be another point higher.

Go with the bigger turbo...Get the wife a safer V8 Mustang
I think that you have forged after market pistons , and your rods will be ok to 6500 or more with the lighter pistons, as long as your boost and tune does not go bad...The stock rods are tough but can be bent with bad tune...of course now that I said this you will have a problem...The after market rod would be recommended.
I would keep the iron head until you are sure that there is nothing left, that's the fun part.

My thoughts:

I wouldn't be concerned about overspeeding the turbo at the boost and RPM you run.

Boost onset could possibly be improved if wastegate control type is poor. If it is being controlled by the HP, a properly set up solenoid and proper (solenoid)tuning, it won't get better on gas unless the (spark and fuel)tune is poor.

E85 can help both in lower RPM torque and boost onset if you're spark limited now from fuel and from the increase in exhaust gas volume. I'd be suprised if your current injectors would suffice, but it can be calculated and inferred from your current duty cycle. I doubt you will get the change you are looking for from just E85 and tuning.

Bottom line!
You can't have low rpm torque or turbo response on a 200 cid engine when the intake valve doesn't close until somewhere after 81 degrees ABDC when the piston is almost half way up the cylinder no matter what the external components are doing or the tune-up.

67Straightsix":2mbkmmgx said:

[bbvideo=560,315]https://youtu.be/WL-jdGl5kxc[/bbvideo]

Click to expand...

In my opinion, remove and replace the blue join to the turbo with a Cobra 62 or aftermarket 70 mm 5.0 throttle body as a gate valve. It will sit with the alternator. With its TPS and a cruise control chain, you can set it to automatically open as a.NAND gate. It would operate only between 800 and 2500 rpm at open loop and then be operative as a flow restriction at about 10 dwgrees to drastically invoke boost off idle to 2800 rpm when it would be at 15 psi.

xctasy

You're fighting 3 things here.
Very late closing intake valve, excessive valve overlap and a very low DCR (5.6)
If you were to go open loop you would find very little help with torque above idle since the manifold vacuum is very low under any load anyway.

Secondly the engine requires manifold pressure just to maintain a steady state highway speed.
It take 4 psi at 2000 rpm to maintain 60 MPH so you can't be open loop at low rpm without loss of power and making turbo response worse.

Like I said earlier, the only band aid that I found to give any results worth the effort was to advance the cam but it is still a band-aid and doesn't address the root cause of the problem.

If you want the maximum width power band there can't be any miss matches in a closed loop system.

Adding a second wastegate will not help. At all. Even if you call it a throttle body.

pmuller9":12a9cny3 said:

Bottom line!
You can't have low rpm torque or turbo response on a 200 cid engine when the intake valve doesn't close until somewhere after 81 degrees ABDC when the piston is almost half way up the cylinder no matter what the external components are doing or the tune-up.

Click to expand...

Agreed. Only minor improvements could be made with boost controller or fuel choice and tuning each. A new cam should be night and day difference in power band and drivability.

It's been a while so I looked back to post 101 where the compressor map is and there is no problem running the engine rpm out to 5500 rpm and going as high as 6000 rpm.
viewtopic.php?p=604272#p604272

The new cam can have an intake duration anywhere between 214 and 220 degrees depending on which end of the power band you want to focus on.
Since you have that great exhaust header which offers scavenging the cam can be a single profile and the LSA doesn't have to really wide. A 112 LSA would be sufficient.

pmuller9":2xrhvkbj said:

xctasy

You're fighting 3 things here.
Very late closing intake valve, excessive valve overlap and a very low DCR (5.6)
If you were to go open loop you would find very little help with torque above idle since the manifold vacuum is very low under any load anyway.

Secondly the engine requires manifold pressure just to maintain a steady state highway speed.
It take 4 psi at 2000 rpm to maintain 60 MPH so you can't be open loop at low rpm without loss of power and making turbo response worse.

Like I said earlier, the only band aid that I found to give any results worth the effort was to advance the cam but it is still a band-aid and doesn't address the root cause of the problem.

If you want the maximum width power band there can't be any miss matches in a closed loop system.

Click to expand...

The intake and outlet control pressure. Ideally, Id like 67StraighSix to welded the chambers of his cylinder head to 48 cc, and keep the cam he's got.

This is a loop I learned from Buddy Ingersoll, Ak Miller and David Vizard. Look at the turbos adiabatic cycle, and be okay with some off beam methods. Dick Johnson had a problem with not getting the help he needed from Ford in 1988 with his Sierra Cosworth RS500. He used two engine management systems, and created a car that made 60 hp un-turboed, and 500 hp boosted, and then switched the fuel deliver systems between each state. The huge reduction in DCR was taken car of by the turbo being feed fuel like a jet turbine to boost it. This is the AR Anthony Rodriguez idea. You can lean fuel out and then slug it suddenly, like the excess fuel factor in nitrous.

Don't be afraid to try the CT Colin Townsend method. If the fuel deliver map and advance is fine, then play with Upstream Inlet and Downstream Exhaust to make transitional boost. The DCR and Cam, they stay the same.

The low compression is the only bad guy here.

guhfluh":2xrhvkbj said:

Adding a second wastegate will not help. At all. Even if you call it a throttle body.

Click to expand...

:|

Its not a wastegate. Its a flow inducer. A feet per second increase by area reduction from an upstream throttle body that gets released when the engine hits target boost. The intake air is harsh and impinges on the normal adiabatic cycle. The turbo impellor is loaded. The exhaust inducer is forced to spin the loaded intake to a higher boost level.


The full article. Colin's turbo was sized too small on a 265, but the concept is the same


https://www.autospeed.com/cms/a_107764/article

The exhaust can be restricted to gain boost. By a cut out.

Either way, it comes on boost quicker without hurting the ludicrously high power output.

Aussie AIT guy have been doing this stuff for years.

And you guys want to change the cam.

I clean floors. Boost pressure goes up when the intake gets restricted or the outlet from the motor gets blocked.

Mitsubishi did this on the Turbo 2.0 Starion and Turbo 1.8 Cordia to improve boost by blocking a really nice exhaust with a ghastly 1.5" plate on the exhaust silencer.

I read the Colins article several times and the conditions are not the same.
A turbo cam was installed that was a close match to the desired power band.
The turbo was marginally small not a gross mismatch and the fix seemed to address the turbo's fall off of efficiency at the upper end of the power band.

That is totally opposite of the situation here where the cam duration is way too much causing the engine VE to be so low below 2500 rpm that there is no chance of making torque even with more boost.

The engine is seeing boost at low rpm but there isn't any significant cylinder fill.
With the long tube header system there is scavenging instead of back pressure and with 65 degrees of valve overlap the intake charge goes out the exhaust during that period at low rpm rather than starting cylinder fill.
The better fuel mileage as the engine rpm increases from 2000 to 2700 rpm at the same highway speed is a good indicator.

At the other side of the cam lobe the intake valve is closing after 80 degrees ABDC pumping the fuel mixture back into the intake manifold before the valve closes.

We already know that at 2000 rpm it takes 4 lbs (18.7 psi absolute at sea level) of manifold pressure to maintain a steady 60 MPH
Even another 5 lbs of manifold pressure will only raise the torque 26% minus the additional amount going out the exhaust.
So 26% (at best) of the small amount of torque needed to keep the car at steady state is not much of an increase in actual torque.
26% of very little is still very little.

Having more boost at low rpm does not solve the problem. You have to increase the engine VE and reduce valve overlap. All cam profile related.
Like I stated previously the only way I have been able to make any significant torque increases in this situation was to advance the cam.
More boost "below cam" does very little.

So yes, I would like very much to see a cam change.

Thank you for all the input - I've learned more about engine theory on this one motor than I have in the last 40 years. In case it's not apparent I'm a fabricator not an engine builder - so this experience has been very educational. (drag-200stang) My wife read your post and laughed - technically this started out as her car and she has hundreds of hours invested in the building of this car - she's sticking with it no matter what!
(xctasy) I enjoy your posts and have learned a lot - but in this case I don't want to do anymore fabricating. I think changing the cam is the simplest way to resolve my issues. If this was strictly a race car I would absolutely work on making this cam work - up high this motor has tons of power. But the majority of the time I am driving this car in the lower rpm range which is wasting fuel. I'd still like to put it on a dyno but all the shops in my area have shut down.

:thanks: gentlemen. Im okay with all that.Your consideration doesnt require anything but an open mind.

When I did my V6 Cortina 2.3 Turbo, same issue big cam duration , IHI RB6, but a C4 auto and drainpipe 4.1 Falcon six exhaust. I used a VPV and a Fuel Control Valve to spike the exhaust richness. This is what Falcon Sedan Delivery called a Method of Chilli. Sadly going full rich doesnt help the exhaust flow on a gasoline car like it does on a Liquified Propane Gas one.

Itll be great with a milder cam. Compression can be added with stick welder. But if youd add a 50 shot of nitrous at 1500 with a microswitch...youll have no lag at all...and be laughing

:rolflmao:

:rolflmao:


:nox:

NX systems icon...page 2

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Have the new cam specs been sorted out?

What valve springs are on the head?

My wife says NOOOOO on nitrous, she has seen to many nitrious motors grenade :nono:
I've been driving the car aggressively to decide how we want the car to perform. Also talked to Schneider cams for their recommendation. Here are the cam specs. I chose.This cam seems to be the best fit for the way the car is being driven. I hope there is not too much disagreement on this.

Pmuller
The current cam has 120-130 lbs seat pressure.

No disagreement. Looks good!

The new cam specs are a little on the aggressive side but it will be a world of difference over the present cam.
I think you have been enjoying the upper rpm power so this cam should still provide that while adding to the lower end of the power band.
Don't be afraid to push the engine close to 6000 rpm with the new cam.

120 to 130 seat pressure is good on a hydraulic lifter cam at this rpm range.
Do you happen to know the spring rate or the open pressure?

The cam card has you installing the cam 2 degrees advanced.
It wouldn't hurt if you installed it 4 degrees advanced.
So if the intake lobe center ends up between 108 to 110 degrees ATDC it will be fine.

Hope everyone is having a happy holiday season! I have a few days off so have been working on degreeing the cam. I degreed the cam with zero advance and at 4 degrees advanced. Here are my results:
0 Advance
Intake - Open 4 degrees BTDC / Closes 40 degrees ABDC
Exhaust - Open 42 degrees BBDC / Closes 3 degrees BTDC
4 Advanced
Intake - Open 6 degrees BTDC / Closes 38 degrees ABDC
Exhaust - Opens 44 BBDC / Closes 6 BDTC
I could not get the timing events to match the cam card

Any information would be very helpful - I think I'm in the ballpark, but should the numbers be more accurate to the card? I've checked multiple times with the same numbers coming up so at least it's consistent.

I sent my header out to be ceramic coated - should be back in a month. So while waiting for that I thought I'd make some improvements: changing the routing of the turbo intake plumbing for more room and efficiency; changing out the front seats for a pair of Corbeaus; finally going to hook up the heating and AC (all those things the wife thinks are important ) etc....