1zz - the next level - Roots Blower...

[Anonymous]

Before anyone flames me, I don't have a flowbench.... In my yoof, I did used A-series heads for £££ and have produced good gains on a Ford Pinto & Rover K-Series.

I have a spare head that I am working up to improve on my last one that I have pulled off the engine. The porting is finished - here is what has been done:

1. Seats opened up to limit of seal band + .020 breakedge (i.e. 3-angle blend)
2. Throats matched to opened seats
3. Short side of port blended to add radius
4. De-shrouded valves to suit 82mm cylinder bore
5. Raised centreline of exhaust port (i.e. exhaust port now rough oval) to limit of header pipe, no work on lower side of port
6. Opened last 3/4" of exhaust port to blend 1:4ish to header pipe
7. Smoothed casting lines

What I did not do:

1. Enlarge inlet port  - it has enough area to suit the valves already
2. Port match inlet port - port in head is already bigger than manifold which is why I am also porting a manifold (again)
3. Fit larger valves - I have +1mm valves here, but want the car back on the road, so when I do the second head I will fit these. They need some proper machining so will cost probably £400 ish to get done. Project for later this summer along with my DLC coated (non sleeves) 82mm block idea

If you are interested, here are pics: http://www.box.net/shared/q245pavr10

[Ilogik]

Wish I knew how to do this sort of stuff.  What sort of  gains would that give you mate?

[Tem]

2. Port match inlet port - port in head is already bigger than manifold which is why I am also porting a manifold (again)

Are you porting the stock plastic manifold or something else?

Pics?  s:D s:D

[Anonymous]

Are you porting the stock plastic manifold or something else?

Yup. There are a few areas that are easy to improve. Port match it to the head, remove & blend a big lip sitting right near the TB.

I did this a while back on the donor engine's manifold only to find it was from a Celica.... This one is the pukka job.

Here are the pics. So far, just started it but since it is GRP it machines like butter - so easy to f**k it up if you are not steady handed....

Pics: http://www.box.net/shared/zupxovv7rm

[ChrisGB]

Porting - 1zz
5. Raised centreline of exhaust port (i.e. exhaust port now rough oval) to limit of header pipe, no work on lower side of port
6. Opened last 3/4" of exhaust port to blend 1:4ish to header pipe

I can see the other stuff being very good, but is the valve curtain area anywhere near as big as the port exit from the head? If not, would 5 and particularly 6 not potentially cost power and allow increased back flow?

Chris

[Anonymous]

Porting - 1zz
5. Raised centreline of exhaust port (i.e. exhaust port now rough oval) to limit of header pipe, no work on lower side of port
6. Opened last 3/4" of exhaust port to blend 1:4ish to header pipe

I can see the other stuff being very good, but is the valve curtain area anywhere near as big as the port exit from the head? If not, would 5 and particularly 6 not potentially cost power and allow increased back flow?

Chris

The curtain area is basically the same as the port section, and what is nice is that the section areas are broadly matched through the exhaust port (primarily because I have not touched the inner section of the exhaust port). Then increase toward the exhaust header. I can also control overlap with VVTi so shouldn't have the usual problem of large overlap at low RPM runining driveability.

[ChrisGB]

Porting - 1zz
5. Raised centreline of exhaust port (i.e. exhaust port now rough oval) to limit of header pipe, no work on lower side of port
6. Opened last 3/4" of exhaust port to blend 1:4ish to header pipe

I can see the other stuff being very good, but is the valve curtain area anywhere near as big as the port exit from the head? If not, would 5 and particularly 6 not potentially cost power and allow increased back flow?

Chris

Chris

The curtain area is basically the same as the port section, and what is nice is that the section areas are broadly matched through the exhaust port (primarily because I have not touched the inner section of the exhaust port). Then increase toward the exhaust header. I can also control overlap with VVTi so shouldn't have the usual problem of large overlap at low RPM runining driveability.

The step on the head to exhaust manifold is usually used to propagate a reflection of the returned scavenge pulse from the collector. Essentially what happens is that the step acts like a "resonant plug" preventing the area behind the valve filling with exhaust gas and also keeping a strong wavefront in the primary pipe. Blending the port to the exhaust manifold reduces / eliminates the effect of this losing mid range and top end, potentially up to 3%. The vvti only works on the inlet cam, so you can tune the pulse to arrive at the correct time in the overlap, but with the step removed, the pulse will be weaker. Generally, back in the day, we used to remove material from around the exhaust manifold flange to create a step. On an 8v Family II engine (for example) it was worth 4bhp minimum.

Chris

[Anonymous]

I can see the other stuff being very good, but is the valve curtain area anywhere near as big as the port exit from the head? If not, would 5 and particularly 6 not potentially cost power and allow increased back flow?

Chris

Chris

The curtain area is basically the same as the port section, and what is nice is that the section areas are broadly matched through the exhaust port (primarily because I have not touched the inner section of the exhaust port). Then increase toward the exhaust header. I can also control overlap with VVTi so shouldn't have the usual problem of large overlap at low RPM runining driveability.

The step on the head to exhaust manifold is usually used to propagate a reflection of the returned scavenge pulse from the collector. Essentially what happens is that the step acts like a "resonant plug" preventing the area behind the valve filling with exhaust gas and also keeping a strong wavefront in the primary pipe. Blending the port to the exhaust manifold reduces / eliminates the effect of this losing mid range and top end, potentially up to 3%. The vvti only works on the inlet cam, so you can tune the pulse to arrive at the correct time in the overlap, but with the step removed, the pulse will be weaker. Generally, back in the day, we used to remove material from around the exhaust manifold flange to create a step. On an 8v Family II engine (for example) it was worth 4bhp minimum.

Chris

When Dave Vizard studied the effects of shaped transitions between head & manifold, he basically demonstrated that the purpose of this area was to prevent reversion of exhaust flow into the cylinder along the short side (bottom) of the exhaust port - and he used a step on the short side of the port to inhibit it and it brought the engine up on cam sooner & reduced caminess. He did not show any top end benefits.

In an engine where your exhaust port is too large (say, all the way upto the back of the valve) then the gas density difference between header & head port is negligible and this creates no resistance to flow of gas back in to the port, however with this head the ports are if anything, undersized for the gas flow. Hence we will end up with a density differential at the section of thead around 3/4 - 1/2" from the header face (having a higher density) which to an approaching gas front (in the header, having lower density) acts as a reflector exactly the same as the a collector.

So, I would tend to agree with you if this were a head with larger sections near the valves, but not in this head. The whole approach I have used is to keep the siamese section of the port and the section 1" - 1.5" in almost the same as original area. Only porting ports where (a) sectional transitions are excessive & (b) the 'weak link' around valves & seats.

I also expect to end up with a ~1mm annular 'rim' between the head and header just to make sure the head port is always 'clear' with assembly tolerances... 'covering all bases'

[ChrisGB]

Chris

The curtain area is basically the same as the port section, and what is nice is that the section areas are broadly matched through the exhaust port (primarily because I have not touched the inner section of the exhaust port). Then increase toward the exhaust header. I can also control overlap with VVTi so shouldn't have the usual problem of large overlap at low RPM runining driveability.

The step on the head to exhaust manifold is usually used to propagate a reflection of the returned scavenge pulse from the collector. Essentially what happens is that the step acts like a "resonant plug" preventing the area behind the valve filling with exhaust gas and also keeping a strong wavefront in the primary pipe. Blending the port to the exhaust manifold reduces / eliminates the effect of this losing mid range and top end, potentially up to 3%. The vvti only works on the inlet cam, so you can tune the pulse to arrive at the correct time in the overlap, but with the step removed, the pulse will be weaker. Generally, back in the day, we used to remove material from around the exhaust manifold flange to create a step. On an 8v Family II engine (for example) it was worth 4bhp minimum.

Chris

When Dave Vizard studied the effects of shaped transitions between head & manifold, he basically demonstrated that the purpose of this area was to prevent reversion of exhaust flow into the cylinder along the short side (bottom) of the exhaust port - and he used a step on the short side of the port to inhibit it and it brought the engine up on cam sooner & reduced caminess. He did not show any top end benefits.

In an engine where your exhaust port is too large (say, all the way upto the back of the valve) then the gas density difference between header & head port is negligible and this creates no resistance to flow of gas back in to the port, however with this head the ports are if anything, undersized for the gas flow. Hence we will end up with a density differential at the section of thead around 3/4 - 1/2" from the header face (having a higher density) which to an approaching gas front (in the header, having lower density) acts as a reflector exactly the same as the a collector.

So, I would tend to agree with you if this were a head with larger sections near the valves, but not in this head. The whole approach I have used is to keep the siamese section of the port and the section 1" - 1.5" in almost the same as original area. Only porting ports where (a) sectional transitions are excessive & (b) the 'weak link' around valves & seats.

I also expect to end up with a ~1mm annular 'rim' between the head and header just to make sure the head port is always 'clear' with assembly tolerances... 'covering all bases'

Ahh gotcha, so you have gone "egg shaped". Really looking forward to seeing the results on this build. It is the sort of thing I would love to do if I had the time and money.

Chris

[Anonymous]

Ahh gotcha, so you have gone "egg shaped". Really looking forward to seeing the results on this build. It is the sort of thing I would love to do if I had the time and money.

That is an excellent description! ... It is more related to time than money ... I am sacrificing many hours of running and gym to get this done!

More piccies

Inlet manifold finished:
http://www.box.net/shared/4uprre2nxd
http://www.box.net/shared/2gnjkvmsb5

Head complete & skimmed - I have decided to run a .030 piston - head clearance at the worst single point, and a .035 averaged over opposite sides of the piston. That means that .006 had to come of this head, it was previously skimmed .005 & the block was skimmed .005 when I first built the engine:
http://www.box.net/shared/bzb2f4eug5

[ChrisGB]

Head complete & skimmed - I have decided to run a .030 piston - head clearance at the worst single point, and a .035 averaged over opposite sides of the piston. That means that .006 had to come of this head, it was previously skimmed .005 & the block was skimmed .005 when I first built the engine:
http://www.box.net/shared/bzb2f4eug5

Kin ell, .051 total off the clearance? Will this be run with the stock pistons or on the 2.0L block with the HC ones?

Chris

[Anonymous]

In ell, .051 total off the clearance? Will this be run with the stock pistons or on the 2.0L block with the HC ones?Chris

Not .051".... 005 + .005 + .006 = .016" off total clearance.... This is running with the 11:1 82mm Wiseco pistons.

I actually ended up fitting the larger valves so my wallet is feeling really empty just now... The head is all shimmed out except for 1 valve lifter #22 that I had to order from Toyota...

Inlet manifold is now back in the car, and is connected back up to the TB. Looking at the system holistically, it is obvious that (a) the smallest cross section in the induction path actually is the MAF tube. Tomorrow I may take some measurements to get an idea of how restrictive it is. I guess I could use a pressure meter over the MAF to find out if it really is a resistance to flow.

[ChrisGB]

Not .051".... 005 + .005 + .006 = .016" off total clearance.... This is running with the 11:1 82mm Wiseco pistons.

Oops, beer maths!

[Anonymous]

Currently waiting on a .029 thick Cometic head gasket, so I did another clearance check on the engine (I read a internet horror story about a Honda engine disintergrating due to pistons hitting the head, albeit at 10,500rpm...)

Since I am aiming on a .030 piston - head clearance, and the gasket is .029 thick, I figured that if I can assemble the head to the block with no gasket then it would demonstrate that I would have at least .029 once the gasket was fitted. To get an idea of how close it would be to .029, I put strips of insulating tape on the piston quench areas. The tape measures .007, or .006 if you really push the calipers hard together.

The engine turned over by hand and then after pulling the head I found only a few close area as shown in these pics:

http://www.box.net/shared/u3hvbbhmg6

Given that the close areas are all at areas with carbon deposits on the pistons, and that the tape did not get sliced or squeezed thin much (it stll measures ~.007 - .005 at the squeeze points) I figure that I will get at least .030 at final build. Damn close....

The .004 skim I have had done to the head has reduced the chamber volume by ~.004 x 3.141 x 1.5^2 = .028 cu.in = .46ml. I plan on running extended nose surface discharge plugs (like in an RX-8 engine) as these take up more volume in the chamber and increase the CR a bit more.

[loadswine]

When you are looking at clearance, do you have to allow for things expanding slightly when they are hot , or the pistons causing a little bit of stretch when they are moving at 7000 RPM?
This is fascinating stuff, liked those pics.

[Anonymous]

When you are looking at clearance, do you have to allow for things expanding slightly when they are hot , or the pistons causing a little bit of stretch when they are moving at 7000 RPM?

Well, .030 is the minimum clearance that Wiseco & MWR recommend. It is also the clearance that the Honda K20 racers run - they run silly rpm's as well...

Bottom line is, rod stretch is pertinent & can be calculated (I am working on a detailled analysis at the mo). Thermal expansion is not so relevant IMHO, since most length involved in the expansion path on the block side are Aluminium, whereas most length involved in the expansion path on the rod / piston side are steel. Given the much higher thermal expansion of Alu compared to Steel and a generally constant temperature throgh the parts, I would expect to see clearance unchanged, or perhaps increase.

The Crower rods I am running I as meaty as the Rods that Honda K20 racers are running so I expect that the stretch I will see will be less as I am limiting to 7800 rpm rather than 9000 or 9500 rpm (even with the long stroke in the 1zz, it is a markedly lower mean piston speed)  *crosses fingers*

[ChrisGB]

Biggest growth is likely to be in the oil wedge. Cranking by hand does not generate the wedge on the crank bearing that running does. Should not be enough to give problems though and should help keep the piston lower at TDC, particularly on the exhaust stroke.

Just be sure that where the tape has been squashed, it has not sprung back up a little. Used to use tin wire to measure these things as it never expands when squashed.

Watching this build with interest. I reckon it is going to be a flier when completed.

Chris

[Anonymous]

Biggest growth is likely to be in the oil wedge. Cranking by hand does not generate the wedge on the crank bearing that running does. Should not be enough to give problems though and should help keep the piston lower at TDC, particularly on the exhaust stroke.

Just be sure that where the tape has been squashed, it has not sprung back up a little. Used to use tin wire to measure these things as it never expands when squashed.

Tin wire? Sounds hard to come buy... May take a run up to Maplin and see if they have really thin solder to use instead.....

But I have waited so long for the gasket that my paitance is running out & I may be willing to take a punt on it being fine. I just completed a nice calculation to provide a degree of reassurance that I will not end up with a grenade the first time I give it some rpm's.....http://www.mr2roc.org/phpBB3/viewtopic.php?f=7&t=24627

[Anonymous]

Finally got the engine build finished with the PPE system. Dyno tuning was a bit of a disappointment as the engine power curve looked exactly as it did when I was running a Che & factory cat; fair enough, it picked up around 4 bhp at top end but that was it. I kind of get the feeling that the custom PPE system is too large in the primaries as it is more commonly used in supercharged engines. I am planning on wrapping the header to see if it improves the gas speed and may give some gains later.

For now, my search for a decent size clutched roots blower has finally ended - the supercharger is a Toyota SC14 displacing 1.4L / rev. To compare, an Eaton M62 displaces 1.02 L / rev so the SC14 is a good sized charger with a compact case and it has a electro-magnetic clutch.

The engine is running a decent compression at the moment so I plan on running retarded intake timing at the low end of the rev range to control det.

So, new decisions:

1) Max-max style switch or proper intelligent control via Unichip (leaning towards Unichip control)
2) TB before or after (leaning toward after the s/c)
3) Intercooler location

Current aim is 6psi boost for ~ 200bhp power band from ~ 3k to 7.5k with ~270bhp peak.

[aaronjb]

Totally silly but it has to be a mad-max style switch - and it has to be a red pull up stopper button on the front of the gear lever  s;) s;)

[enid_b]

i dont understand a word of this, but the pics are nice, and it sounds great. whatever it is.

[ChrisGB]

Finally got the engine build finished with the PPE system. Dyno tuning was a bit of a disappointment as the engine power curve looked exactly as it did when I was running a Che & factory cat; fair enough, it picked up around 4 bhp at top end but that was it. I kind of get the feeling that the custom PPE system is too large in the primaries as it is more commonly used in supercharged engines. I am planning on wrapping the header to see if it improves the gas speed and may give some gains later.

Interesting that the gains are that small. What are you using as an exhaust system?

Chris

[Star_69]

The unichip q has duel maps doesnt it? That would be cool, one for boost and one without. Madmax switch or 'Eleanor' GO BABY GO button on gearnob to switch maps and engage clutch followed by a loud whine would be awesome   s:D s:D