TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

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mike1157
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TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #1 by mike1157 » Fri Dec 30, 2016 8:57 am

Well, the Monster is legit. He is a bonafide street car.
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I decided against the personalized plate. The reason for that was simple. I did not want to have to explain a bazillion times what it meant when only the twelve of us know why it's called GMONSTR.
Other contributing factors were that the state of Alabama decided to charge me for all three years that the car has been in my possession despite the fact that it has been non-running.
So,...I paid $171.00 to license the Monster today,..when I was expecting 70.

I intend to modify the coverage I put on the Monster to include a stated value policy, But for the sake of what I wanted to accomplish today, all I needed was proof of ins.

It did drive the distance. There and back was about a 20 mile round trip. I'm starting to become concerned that what I think are 3.55's are way deeper than that. It seem that the car runs at 2400-2600 RPM at what I think is 70 MPH. I still need to properly calibrate the speedo to be sure,..but it's like the engine is spinning way to high to be in 4th gear to be a 3.55.

I'll have to look into that more.

After I got it back I removed the Autolite 65 plugs (which looked perfect,..IDK why I decided to go colder0 But I installed a set of 64's that I have had since day 1. I gapped them to .032, and then took the car for a drive.
This thing detonates so bad when you try to put your foot on the floor that had these been hyperU craptic pistons, they'd be broken by now. I'm only talkin about 1 second of that, but there is clearly something wrong.
When I roll into the throttle, as long as I keep it at about 1/2 throttle, it pings. Stand on it, and it freakin rattles.

Here's my new Auto- Hypochondriacism.
A long time ago I was building a Clevor that I intended to put nitrous on.I planned to use a open chamber 2v head. After reading and talkin to people, I learned that the lack of a "quench area" would cause the engine to detonate very easily.
Consequently,..I bailed on the Clevor thing, and just went w/ a conventional Windsor head instead. I never got to see for myself whether or not that head was gonna cause rampant detonation.


This is a pic of that chamber.
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And this is the closed chamber version of that head. The flat area is necessary to promote a clean burn, as it forces more complete combustion as a result a tighter packed mixture.
Image
Now,......this is the Monster's camber:
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I'm not seeing no quench.
I knew this in the back of my head, but gave it little consideration, hoping that it wouldn't be an issue. Now it may be that this is why the thing is rattling.
Then again,..It could just be tune related. Time will tell I guess.

If that turns out to be the case,..it'll be the death nail for any boost north of probably 5 P.S.I. as this all ties back to lack of quench being intolerant of high cylinder pressure,..and even that seems to bring on the rattle.

This car is running megasquirt, it is injected, and has a 66mm Turbo on it. The tune right now puts it in the 11:1 AFR, and 18 degrees timing range when in boost. Surely I can't be the only guy in the world trying to turbocharge this engine w/ this head on it?

If I can't "tune out" the detonation because of the open chamber, what kind of power can I expect from this thing Dean? (Yeah,...I know you'll be looking in,...MOF, I'm expecting that you will);)
1978 Ford Fairmont Futura project: "The Gila Monster" Xflow'd Megasquirted, MPFI'd, DIS, T/C'd, A2WI/C'd 250, 4R70W shifted, and 8.8, 3.55 gear rearended.

thesameguy
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Re: TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #2 by thesameguy » Fri Dec 30, 2016 9:52 am

You say the tune should put it at 11:1, but do you know that's actually happening? Are you datalogging or at least watching AFR on a monitor/gauge?

drag-200stang
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Re: TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #3 by drag-200stang » Fri Dec 30, 2016 11:20 am

Google...chamber softening page 3 yellow bullet.
66 Mustang Coupe
200 turbo w/lenco 4-spd
stock adj. rockers, stock timing set, ARP studs
best 1/4 mile ET 9.85/best mph 139 on 8 lbs progressing to 15 lbs boost
Went 9's when 10's was fast.

pmuller9
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Re: TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #4 by pmuller9 » Fri Dec 30, 2016 1:59 pm

If you were to scribe the cylinder bore on to the head surface it would look like this.
There is some quench area. This is not an open chamber.
Image
The other questions would be:
What does the piston head look like?
Is the piston at zero deck height at TDC?

Quench helps minimize detonation but the amount of detonation you are describing indicates a problem elsewhere.
Timing would be the most significant.
Have you checked the timing with a light against what the megasquirt indicates it is?

What are the cam specs?

drag-200stang
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Location: Michigan

Re: TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #5 by drag-200stang » Fri Dec 30, 2016 2:30 pm

Some of the smartest and fastest guys are now dishing the quench pad on boosted, NOS and some NA .
I do not think it is because of not enough quench ether....what is the compression, how much turbine inlet pressure,octane ?
Like said, made sure your tune is was you think it is.Make sure emi is not jacking your timing.
Maybe a couple of injectors are not fueling right...what about oil getting in the chamber, that with cause detonation.
66 Mustang Coupe
200 turbo w/lenco 4-spd
stock adj. rockers, stock timing set, ARP studs
best 1/4 mile ET 9.85/best mph 139 on 8 lbs progressing to 15 lbs boost
Went 9's when 10's was fast.

mike1157
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Posts: 181
Joined: Sat Aug 03, 2013 9:55 am

Re: TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #6 by mike1157 » Fri Dec 30, 2016 4:59 pm

Thanks guys,...worked on this all day. I think I'm close (If tire smoke is any indication of that)

The car needed a ton of timing taken out, and yes I'm datalogging each test. We originally had a steep curve into 100kpa and beyond from "cruise timing" up into the boosted areas of the timing chart. Too much timing M.O.F.

Now my cruise timing is at 27 degrees and falls off to 14 degrees at 200kpa w/ 16, and 18 degrees steps respectively where boost begins.

The AFR was also smoothed into the "fat zone" so that the cruise AFR wasn't so drastic a jump once the engine started seeing boost. Now the AFR table is much more gradually "fat: as the engine starts to transition from vacuum into boost.

The pistons are Racetec 2618 3.700 bore forged flat tops. The cam is a solid roller w/ 550/540 lift numbers, and 225-235 degree duration at .050 I beleive ground on a 112 C/L and installed at 110.

After the last timing changes I'm making really good power. Boost comes on even going up a gradual hill w/ very little throttle ( like 25%)
The car is a heathen,...it takes very little throttle to get the rear to start coming around..all of this just occurring today.

It's exactly what I wanted. To take a 6 banger,...notorious for being slower than a glacier,..and adding some unorthodox stuff to make something that nobody else will have, while at the same time making the same, if not more power and torque than a mildly modified BBF.

Thanks to everybody that chimed in to help...
1978 Ford Fairmont Futura project: "The Gila Monster" Xflow'd Megasquirted, MPFI'd, DIS, T/C'd, A2WI/C'd 250, 4R70W shifted, and 8.8, 3.55 gear rearended.

pmuller9
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Location: Columbus, Indiana

Re: TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #7 by pmuller9 » Fri Dec 30, 2016 5:53 pm

Great Job! Nice choice of parts.
Keep us posted on how it runs and all the V8s that get spanked along the way.
Gotta love it!

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First Fox
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Re: TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #8 by First Fox » Sat Dec 31, 2016 11:35 am

It's great to see your project up and running Mike. You have done a ton of unique, nice work and stuck it out till the end, so kudos!

I just wanted to add that in my experience if you are boosting at 1/4 throttle the turbine and or hotside A/R may be too small and is subsequently overheating your intake charge. This would certainly give you detonation issues. Just food for thought. And again, great job!
My garage:

1962 Falcon. 170/Auto.
1965 Fairlane. Twin turbocharged 289/4 speed.
1965 Thunderbird. 390/Auto.
1980 Fairmont. Turbocharged 200, 260 Comp cam/T5 and '93 Mustang steering/suspension.
1981 F-100. 300/4 speed OD. I use this primarily to haul my cars home after I modify them and they break.
1987 Thunderbird Turbocoupe. 2.3/T5. Porche designed 16 valve, twin cam cylinder head.


Image

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xctasy
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Re: TC'd 250 w/ Crossflow head,...runs good enough to drive,...detonates in boost.

Post #9 by xctasy » Sun Jan 01, 2017 2:30 am

:hmmm:


The Borg Warner S300 SX 3 twin scroll, T4 flanged 60mm is capable of 450 rear wheel HP according to Reed at Work Turbochargers in Pelham.

Maybee its okay to boost modulate at the 25 to 50% throttle zone to pull out heat.

Cut the boost to 3.5 psi below 1500 to 2800, 25 to 50% TPS

Lotus Enginnering did this for the Lotus Esprit T3 60 turbo it put on the 1983 to 1990 MG Mtero 1275.

That car had a Cooper S style engine 1275 A series 9.3:1 compression. They used stock tractor cam timing, yet there was a non split lobe 268 cam used on the non turbo whic absolutley woke the engine up.


http://www.mgownersclub.co.uk/mg-guides ... etro-turbo


The problem was that peak torque with even low levels of boost would damage the gearbox so boost was set on the wastegate at a low 4 psi. However, at 4000rpm or higher an electronic module would allow a controlled leak from the sensor hose going to the wastegate and would allow air to ‘leak’, so that the wastegate actuator would see a lower pressure and would not lift the wastegate valve off its seat. That allowed the boost pressure to rise and only when it reached 7psi would the module then close off the ‘leak’ and allow the wastegate to move. It would then modulate the leak to maintain this raised boost pressure until rpms dropped below 4000rpm.



Ford Australias development engineers put the "kybosh" on any Turbo Falcon from 1986 to 2003, due to the amount of low end torque a 4 liter turbo I6 produced, and its effect on production Borg Warner 3 stage and BTR 4 stage automatics.

Basically, the first turbo Falcons from AIT used the T3 60 turbo and a really moderate boost to try and eliminate transmission carnage. The early HF1 headed EFI engines went right to 360 lb-ft at 2800 rpm, with a fairly flat curve from off idle to about 3500 RPM with just a 256 degree, 445 thou lift hydraulic cam.
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FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
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