It's going on a 170 slant six. I really don't think it will flow enough on the intake side for a 225 to make it worth the trouble.

Frank

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Franklin
'61 Valiant

Do you have a picture of the rocker assemblies? Do all your lifter bores/pushrods line up well?

Looks like a great set up, Hope it all works out.

Rick

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Official Cookie and Mater Tormentor.

You can order about any aftermarket racing part for the 3TC that you can conceive of. Around the world these Toyotas are popular race motors. A double overhead cam "export" 3TC also exists, big port versions were built. Custom rocker arms and large valves are available.

The 3TC is not a thin wall casting, I believe some blocks can be overbored more than .100. When Chevy was building the Vega, Toyota was focusing on fundamentals, the 3TC design is conservative and like the 20RE it is overbuilt and indestructible, capable of handling 600 HP with a blower. The pushrod 4 and V8 Toyotas were clearly patterned after the Mopar Hemi, but closer in scale to a '57 Dodge 325 than the later 426.

With a mild cam, low compression and small valves the 108 cubic inch (1,770 cc) 3TC makes only 90 HP, but a mild 225 would produce 187 HP when built like that. I think this style head on a race 225 could produce more power than the Slant Six block might handle.

I figure a racer could use custom rods and 3TC pistons from Wiseco. With all the recent talk of E-85 a special built limited use alcohol burning high compression street motor might be practical.

Actually the Toyota DOHC 3T engine is also turbocharged making it a 3T-GTE. 3 is the 3rd major variant of the type, T is the engine family, G is the wide valve angle sports type head rather than F for the narrow angle economy head, T is turbocharged and E is electronic fuel injection. It even has twin plugs for each cylinder. The 2T engine twin cam was the 2T-G. There were never any US market Toyota cars with twin cam T engines. The T engine's mechanical limits are around 300hp and about where the main caps start to go with the crank also being near it's limits.

At one time I was seriously considering buying this car:
http://www.sdsefi.com/features/may99celica.htm

It would make 320hp for a while, but the boost and RPM were reduced to make about 280hp so it would last a season of racing.

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Joshua

I'm confused. Are you proposing that the aluminum slant head be based off the Toyota head?

Looks like you have one in the works, what kind of car to you plan on using it in? A tube frame dragster?

I guess I just don't understand the point.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

Zedpapa,

You might look at the 2.2/2.5 FWD head for some input on the new aluminum head you are looking to design. The 2.2/2.5 and /6 both share almost identical bores, strokes, valve sizes, etc. I am convinced that the 2.2/2.5 was based on the /6. The later swirl port 2.2/2.5 head has a fairly modern combustion design.

I know of one 2.5 that made 440 hp on a chassis dyno with a ported 8V head. He had a big turbo to help him, but it does show that the 8V head could make power.

You might also look at the 2.0/2.4 Neon/Stratus motor. I know it is a 16V head, but it is an evolution of the 2.2/2.5 which (IMO) is an evolution of the /6.

Just a thought.

An OHC design like a 2.2/2.5 would be cool. Maybe not realistic, but cool.

Don't give up!!!

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

I think the Hemi head could only go into a special race chassis. I believe the intake valves would be on the passenger side, there would be litttle room for an intake unless the motor were oriented to be upright, or better - tilted the other way! This idea is for a toy for someone who has lots of time and money to spend, but I believe the 3TC head is one of the better existing design patterns as it is pushrod, and is based upon the admired Hemi design.

I believe one aftermarket CNC milled 3TC head is available which flows better than the OEM design. Perhaps the folks who build CNC head could build one for the slant six. You could use aftermarket rocker arms and not use a single Toyota piece.

Make a visit to the local salvage yard and look at the 2TC and 3TC and take a look under that familiar looking valve cover.

People are putting on neon/stratus/caravan 2.4L etc DOHC heads onto 2.2/2.5 block with some machine rework (well within lot of people's budgets) and set of adjustable cam spockets.

Look in 16 valve conversion in www.turbododge.com forum.

I'm collecting parts to build up a n/a 2.5L with DOHC and megasquirt for my carbed 2.2 caravan. So far, got early T1 9cc dished pistons, and waiting for one guy to send in stratus complete top end with that DOHC head.

The rework involves plugging the oil holes and putting in external drain back and oil feeds, longer timing belt, and pair of adjustable spockets,
drive it with custom programmed computer or megasquirt, SDS etc.
Turbo'ed successfully.

Oh, the 8 valve head flows POORLY, look at the 287/782 (bathtub & swirl chamber respectively) ports, intakes goes in at better angle but the exhaust port flows out from chamber goes nearly 220 degrees turn. ICK! DOHC head flows much more and this is also another reason to replace chrysler original 16 valve heads because the parts for them is getting harder to obtain and fewer heads available, much expensive. DOHC heads is plentiful and cheap.

Cheers, Wizard

Even a SOHC Neon head flows quite well and could be easier to package. It's also one custom billet cam to have made instead of two. Too bad the bore spacing is so far off.

One problem with the slant 6 that I haven't seen addressed is the uneven bore spacing. There is wider spacing between cylinders 2-3 and 4-5 than between 1-2, 3-4, and 5-6. Of course the easiest thing to do is ignore the .020" difference. One thing I don't know is if the head bolt pattern reflects the difference in bore spacing and I don't have an engine here to check.

It's already known that the Supra M series bore spacing is smaller and doesn't come close to the /6. The Nissan RB25 engine has an 86mm bore, but I'm having trouble finding the bore spacing dimension. Maybe someone in Australia could help?

Also the Datsun 280Z engine (L28) has remakably similar bore and stroke to the 170. The L28 is 3.39"x3.11", but again I have no idea what the bore spacing is.

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Joshua

The classic Jaguar double overhead cam six also has a 4" bore center spacing. It is a hemispherical chamber design. The Jaguar bolt pattern is 4" between the cylinders, but slightly wider to account for the width of the head. Jaguar bored their blocks to the extreme considering the casting technology of the day. To allow for water circulation between the bores Jaguar cut slots into the deck of the block. I think the Jag six was sized up to 3.66" bore with a 4.19" stroke. In the 1980s Jaguar briefly introduced an oversquare six that is unlike the earlier design. The early Jaguar hemi chambers worked well when high compression was okay, but did not do well with emissions regulations, later heads have quench pockets.

The Jaguar was admired in the 1950s as the highest output production motor of the era, I believe it is reasonable to guess that Mopar used the dimensions of the 7 main Jaguar block as a design pattern for the economy oriented the Slant Six. The Slant Six is a lighter motor, the Jaguar had crankshaft problems with the long stoke high output motor, they made the block very heavy ( boat anchor ).

The relatively large bore Jaguar is a hint that a siamezed Slant Six race block might be a future consideration, with a nominal 3.65" bore spacing with room to go a bit larger.

www.turbododge.com and www.thedodgegarage.com have info on flow datas for SOHC, 287 and 782 heads and everywhere else had DOHC flowed. Exhaust particularly flowed more on DOHC even the intake flowed more as well.

And they do say that SOHC flows about same as 782 on exhaust side so gives less effect and is only suitable on 2.0 n/a. 2.4, 2.5 are larger and can hinder the power output if using SOHC instead of DOHC head.

Cheers, Wizard

I wasn't so much suggesting modding an existing head, or trying to use a DOHC head as I was trying to give a direction to look at in the design of the aluminum head that was being proposed.

I agree that the DOHC far outflows the 8V head, but the crossflow design doesn't lend itself to the /6 in a car chassis.

Also, the 8V head can make hp , for example Gary D at over 440 hp at the front wheels before a rod let go. Can a 16V outflow an 8V? Better believe it. Unfortunately, a 16V design wont work in this example.

Not sure, but it doesn't look like a 2.2/2.5 8V flows as well as a /6 head, so maybe port design isn't something to copy. The combustion chamber is definitely more modern, though. That was what prompted me to post.

I thought it was just something to look at.

BTW, I remember when the first 16V conversion hit the streets. If my LeBaron wasn't so worn out, I would love to build a 16V conversion. Now I would rather have a RWD car.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

DionR,

What make you change mind to have RWD car instead?

To all:

Oh, I forgot to add, there is a reversed version of DOHC head found in some cars using chrysler block and a DOHC head with intake and exhaust reversed. That means head had intake on back, exhaust out the front. This said head is called 420A.

Cheers, Wizard

I take it back. At least on the intake side, the numbers I've found for a stock /6 and stock 2.2/2.5 are almost identical.

Lift .400 .500 lift
/6 147 158 cfm
2.2 145 157 cfm

All of the 2.2/2.5 numbers I found were for the later swirl port heads, 86' and later. From what I remember, the earlier head (called the bathtub head) was supposed to flow better, but I didn't come across any number for it. The combustion chamber was completely different and used a different ignition curve, plus the chamber was larger and required extra parts to make work on the later motors. Most people just ported the swirl head.

Also, looks like the /6 head is better ported. Most of the .500 lift numbers for the 2.2/2.5 were high 180's.

FYI, the Neon 16V head looked to be probably 90 cfm better on the intake, stock. Maybe custom motor mounts, trans adapter plate, and hood bubble would allow us to rotate the motor up and allow a cross flow head.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car