The Best of 2010: Extreme Engine Tech, Technosquare's Monster Naturally Aspirated Toyota 4AG part 3

Great article ! I've been waiting for this chapter.
I was hoping this engine would put out some 220-230 hp......but....
I guess like you said, with some 321 stainless steel headers, Burns collectors, and maybe new valves and seals, we could see some more power.
How about playing around with the stack velocities lenght?
What kind of compression do the pistons have?

"Engine control is managed by an Autec stand alone ECU and CDI system."

Autec?

Autronic.

Can you expalin the coolant bypass hose some more.

I am not familiar with 4AGs, but from the pics. it looks like it connects to the outlet to the radiator and sends coolant directly from number 4 to the radiator. If that is correct, how does this help cooling number 4?

How was it determined that this was necessary to do. I am wondering if other engines wouldn't benefit from something like this also.

The very best TRD Atlantic engines would put out 230 crank hp over a very narrow powerband. This was with a better header. Header technology is even better now days with stepped primaries, true merged collectors with venturis and reverse megaphones. Considering that this engine has milder cams than a typical Atlantic engine, the power output is right in line. Technosquare ended up running 304/304 TRD cams which was considered to be a rally combination. Atlantic and GT engines ran 320/304 but this was for lighter true race cars.

The engine is a little over 13:1 like Atlantic engines.

The head on this engine isn't so great, especially the worn sunk valves. The valves are really on there last legs with the margins knife sharp and the 45 on the seat below the CC deck! They are two valve job past usable but the owner didn't want to spend the money on new valves. Hasselgren has a huge rep but the head and port work was disappointing. Technosquare touched it up but could only build to the owners budget and what he ultimately wanted to do. There is a lot of power lost in the head. Sunk valves kill flow.

I think this engine could easily be at 200 wheel hp and 240 crank hp with a better head and header. RWD cars loose at least 20% to the rear wheels.

As far as Autec, that is sort of Mike slang and it slipped into the story. Since Autronics was started by an ex Motec engineer, I have always called them Autecs when talking with my industry friends. Sorry!

For water bypass, a lot of engines can use this bypass. I have done it with the QR25DE turbo engine in the Dog III and we used to do it in the 152E 2 liter race engine back in the TRD days. Its pretty common for I-4 cylinders to have the back cylinder get hot.

If in the development of an engine, you have evidence of the rear cylinders running hotter, this is a trick to try.

This is more wheel hp than I have ever seen on a NA 4AG, even on a dynojet.

Very respectable power for a 25-year old production engine design, IMO. Love the dry sump!

How is the coolant bypass done. I'm curious, particularly on the QR. From the pic it just looks like you drilled into the coolant galley. Maybe a future article?

Thanks for clarify the details Mike.
I remember you saying the valves are worn out and the headers' design is not optimal to today's standards.
I was gonna mention Hasselgren but you anticipated me.
I remember few years back when they lend one of their AE86 to Keichii Tsuchiya, and he ran it at Willowspring....and blew the engine.
If I remember correctly, that engine made some 250-260 hp, but not sure.
It had the injectors located outside the velocity stack, pretty trick...
Sometime I don't understand people, the owner of this 4AG spent some serious dough on the engine with dry sump, stroked/ billet crankshaft, port and polish, and skip on the valves.....oh well.

Look, I dig the penile value of a dry sump system. But. You knew there was going to be a but, but- baloney. The black and silvertop 4age have an 8200+ fuel cut. Why again do you need a dry sump? The miata B6? Yes. The 4age? Built for it. No need for a $2000 dry sump.

Brust-The racing 4AG does need a dry sump for any kind of reliability under racing conditions. I have been involved with maintaining and building many 4AG powered REAL race cars and the bearing life is just a few hours even with a dry sump. I suggest you read the article carefully where the reasons why are laid out very clearly.

JDM- Lately I havent been too impressed with the quality of Hassegrens work. This head was a joke.

I see...I always heard good things about them, but never dealt with them personally.
Did you (or did Technosquare) measure the CFM before and after porting the head?
Thanks again Mike for the quick response.

No, the cars owner provided the head. It was so bad that Howard touched it up but it needs new seats, new valves and some more porting.

The porting is permanent...once it's ported, it's done.
Did Howard @ Technosquare cut the valve guide for more flow?
We all know the valves and seats have to be replaced sooner or later based on how many hours the engine sees on the track....that's racing.
Get some Burns 321 stainless steel and some merge collector-another $2000 should fit the bill.
Tell the owner to build it right, or sell it....lol

Thanks for the articles --- nice read (I think I will keep my 5AGZE details to myself LOL)

Re: dry sumping: Fair enough. Just thought that with the toyota building them with 8200 rpm fuel cuts, the stock oil pump would be fine. I don't have racing experience, so will have to defer to your firsthand knowledge. I know you haven't gotten the standard "why not turbo" yet, but I'll just add that there are people building very flexible turbo engines with a midrange, street setup at 225WHP (see Brent Picasso's MR2) on bare bones budgets. Seems like NA is great for the sound, but for the numbers a couple grand and a t25, 16g, or K03 makes for a much better engine for the normal guy.

JDM- The guides are slightly cut and the bosses are profiled, but on a 4AG, they are not that long for lateral load support and considering that on the exhaust valve, it the main way heat is conducted out of the valve, it is not advisable to completely remove it for a car that is going to be at WOT for long periods of time. Howard mostly did touch up work opening the port near the seat area and unshrouding the valves a little because they were sunk so deeply. I dunno how Hassegren represented this head to the customer but it was pretty shoddy work, perhaps the customer had a limited budget so they did a crappy job. I have been disappointed with other work I have seen from them lately as well. Note that this does not reflect on Technosquares abilty.

Davegt27- Seen some of your build specs on Club4ag. We would like to see how your motor comes out as there are not as many well build 5AGZE's around. I remember Taka Aono's didnt put out that much power, years ago when I first met him.

Brust- We are going to do a Turbo 4AG build which is going to be a look inside Taka Aono's motor soon.

Your cam settings seem to be a bit narrow on the lobe split.
Is that because you went with such long duration ?
With my experience with 4valve engines, I would have went with less duration,
wider lobe separation, and with them retarded a few degrees.
300+ duration seems much for the less than 10,000 rpm that the engine is running at.
In fact, your RPM ranges seems extremely mild.
I run the numbers on that rod length/stroke combo, and even at 12,000 rpm, it comes up way below the acceptable max piston acceleration of 140,000 ft/sec/sec.
Did you choose such a low max rpm because of gearing limitations ?

A lot of reasons why this engine is spun at a relatively low rpm is due to the lack of structural integrity of the entire engine. This is an old engine and it was one of Toyota's first attempts at low mass design. This was done without the aid of modern analytical tools and modeling. Hence this is an exceedingly weak engine. I was an engineer at TRD during this engines developmental heyday and we had all sorts of issues with keeping them together.

Block flex, main cap walk, bearing issues, oil pump gear and crank failures were all part of what we ran into, hence our paranoia here, like in filling the block, and using the formula Atlantic parts to stiffen things.

In testing and development back in the old TRD days, we found that this engine likes tight lobe centers as many engines form this era did. A lot of it I feel is due to poor port flow and a poor stroke to rod length ratio. Although it was a landmark engine, the head doesn't actually flow all that well compared to more modern designs. The "official" TRD Japan recommendation for lobe centers was 98/100.

I have found that an exceptionally good 4AG ported head will indeed like the lobe centers spread a bit more than this example. I would really like to see what this engine would do with a well prepped head and a modern header design.

Mike,

Yeah, after thinking about the lobe split, I guess I am looking at it from the forced induction, and/or auto trans stand point, were power band width is more important than peak numbers.

I would love to hear your thoughts on a high rev 7MGE.
Seeing that you consider the 4AG block somewhat flexable, you would probably cringe at what I am doing with the 'wet noodle' 7M.

I would like to pick your brain on any info you have for the 7M, as much of what info there was on that old war horse has long since vanished.

Is there anyway I can contact you?

The 7M is a pretty robust engine. However we did not develop it very far as it was only raced in Escort World Challenge, the precursor to the current world challenge series. That that time, the Series was a limited prep class and all we could do was exhaust, boost and cooling mods as I recall, the powertrain had to stay largely stock. If the engines coolant and oil temps were managed and the power levels kept reasonable, it was a strong and relaible engine. I kinda recall that experiments with higher power 7M's lead to rod bearing issues but bear with me that this was 25 years ago and I forgot most things.

It is pretty difficult building a high rev I6 because the crank goes through a second order torsional harmonic around 7000-8000 rpm depending on the engine and its hard to keep them alive long term if the engine spends much time there. You will probably have issues with crank and oil pump failure. Just ask Steve Mitchell and Eric Hsu what a headache it is to keep an RB alive at high revs.

The I-6 does have perfect primary balance and with its 120 degree firing spacing, its easy to design effective intake and exhaust systems. It also sounds better than anything excpet a V12.

Well, about the only problems I have had with turning them 8500, is repeated failures of the flex plate bolts, even ARPs.
Solved that finally by dowel pinning the crank.
No problems with the oil pump, even with it being overdriven by 15% (smaller pump pulley), and 80 psi pressure.
The last one I tore down did have some funny looking marks in the main bearings, so I know it's on the edge, but it is an early block with the thinner main webs.
The next one will be on the late block.
I just found a short stroke billet crank out of Japan that should be interresting.
That and longer rods will bring down the piston acceleration down to a safer level.
Right now I am exceeding 140,000 ft/sec/sec just a tad.

And your right, they make music, that's for sure.

Hi,
Just wanted to drp a line and thanks everyone at MotoIQ for what is to me the best car prep site I have ever seen.
Normally engine builders keep they're stuff to themselves but here it's all cristal clear.
Thanks for all the hard work it sure takes you guys putting this up for the delight of some petrol heads like me.

Pedro Amaral
Portugal

Glad you found us Pedro!

Ditto for Marillionado. Looking forward to the turbo version.

amazing...

I was hoping for the next installment where they dial in the cams or maybe something about tuning. I spend hours and hours on one of those dyno programs trying to come up with timing specs, the whole time I am not even sure that's the way to do things.

Great article! I've read all 3 parts now repeatedly. :)

Mike can you suggest a head porting shop for the 4ag. i was going to send my head to hasselgren but after reading your comments i changing my mind. i was also thinking of DPR but i wanted to see what you suggested.

Portflow Design

Does Technosqure sell prebuilt engines like this or no?

Loving the build!