8v 2l Twin Charged -my Little Project

[ToonRboy]

No worries buzzed,

Cool project. As for the Rotary statement, you know what I mean. Everyone knows it has four "strokes", but it puts out 3 power strokes per shaft revolution vs 1/2 for a typical 4-stroke. So, point being was how it flows gasses (similar to a 2-stroke, which puts out 1 power stroke per crank rev).

Speaking of flowing gasses, Garrett uses lbs/min and Mitsubishi uses cfm. Carburetors use cfm, injectors lbs/min. Wheels in inches and tires in milimeters. They can all be converted for easy use in formulas. However, speaking in terms of boost alone means nothing as a Garrett GT T3-60 trim will flow ~490cfm at 14.7psi and a Mitsubishi TD06-18G will flow ~590cfm at 14.7psi. Big difference.

BTW - I too use lbs/hr (turbo flow) in the math equation because that's how the injectors are rated. But conceptually, I can grasp cfm better when it comes to air. Bottom line: you gotta burn the fuel to make the power, and to burn fuel you need oxygen. "Boost" is useful after the turbo is chosen and characteristics known.

I'm definitely with you when it comes to magazine and crank HP. I was kinda doing the same thing (regarding driveline losses). You stated your target at 350 rwhp, so I added ~25 to get crank HP. Then worked backwards to come to the ~38lb/min of air flow you mentioned. That put me in the same spot on the flow map you mentioned as well (PR of 2.7, upper right hand side extent of the peak efficiency island). The turbo you chose is clearly holding VE at that point. I don't know if I'd want to be so close to the choke line. Though with just 2L spinning her up, and the right turbine trim and housing, you shouldn't get there till your upper engine RPM anyway. So, in all likelyhood a good choice. My concern is the high boost with this engine, not to mention the combustion pressures.

Since you're running the SC, couldn't you afford to wait longer for the turbo to spool-up, and use a bigger one which will arrive at 80%VE and push your 38lbs/min at just 1-BAR (PR 2) comfortably, and w/plenty of "head room"?

Granted, not all these maps are 100% accurate. This GT28R 60mm, 60 trim .60 A/R is too much turbo, but you see what I'm getting at?

[Biba69]

On 05/08/08 I commented: "Some years ago I also exchanged a number of emails with Jim Steck (in the US) and I mentioned this monoblock since Jim was in the process of making his own for the Bonneville TS. Jim felt there were inherent flaws in the Australian design and designed his as a combination of girdle and monoblock."

A few days ago I received an email asking what Jim's concerns were about Beninca's mono-sleeves. I simply cannot find Jim's comments - we exchanged over 130 emails either directly or over the Alfa Digest. The following disputes pretty much what I said, but note the date was 10/13/01 and I don't believe Bonnie had run at Bonneville yet:

"Beninca has some really serious turbo engines. I wanted to use one
of his mono-sleeve blocks for the Bonneville engine, but the guy
writing the checks thought it was a little 'over the top'.
Something you can do to increase the rigidity of the engine, without
spending any real money is to epoxy the liners into the block. It
adds a day to the assembly process . . . I install the liners, install
the head with a used gasket (using normal installation torque) and
then let is sit a day. Once the epoxy has set, you can take the
head off and assemble the engine normally. Oh! . . . no o-rings
used at the bottom of the liners. This will also help the head gasket.
It doesn't have to absorb any liner movement . . . so no blown head
gaskets even on very high compression / boost engines."

I'll also include the following email. Please note it was dated 07/21/01 so ignore the dollar figures/comment:

"Hello Biba

"I sell as a complete package.
Alfetta block prepared with oil squirters and No 2 & 4 main bearings
with oil supply.
Mono sleeves bored with strain plate to 84mm and the deck height set to
standard with a "bit" groove.
The barrels can be later bored to 86mm+.
I have run up to 700HP with a turbo.
Cost $3500 Australian excluding duty, taxes and freight.
1 American dollar buys 2 Aussie dollars."

"Thank you
J Beninca"

Since I'd forgotten the email from Jim above, take these comments in the context of someone with a faulty memory: I am pretty sure Jim (later) felt the OZ design didn't allow for sufficient water cooling. It is quite possible the addition of the girdle was solely (???) for the later Bonneville TS engine to help hold it together at what I imagine was Very Maximum boost.

Personal comments: Strictly eyeball engineering but the TS block with its additional strengthening ribs HAS to be stronger than the Nord block. Also, the TS head HAS to flow considerably better than the 50's designed Nord head.

Looks (?): There is going to be so much plumbing for the turbo and supercharger, along with the intercooler it's going to be hard to even see the engine, let alone anyone being horrified that a (gasp, gasp) TS was installed in an Alfetta GT. Yes, you'll have to deal with the extra engine height. I suggest you make a slightly modified carbon fiber hood with a bump for clearance in the front. Once you've made and paid for the mold, I'll take one.

If you disagree, why not make it a Real challenge and start with a - first of the Nord breed - '55 ('54?) 1300 Giulietta engine. (Meant only as a small poke in the rib - I don't do icons).

Biba

[giuliettaevo]

why not make a new valvecover to cover up the TS head you know you want to use? just make a new one with the loo of the older one...

[Greg Gordon]

ToonRboy,

You started to lose me at the part where the turbo had "80%VE". As far as I know turbos don't have rated VE numbers. I think you are talking about adiabatic efficiency not "VE".

Regarding the weight vs volume issue, I prefer to go by weight because that's what the engine does. For example, your O2 sensor leans the mixture out to 14.7:1 by weight, it doesn't know or care what the volume is. You engine also burns and inhales a given weight of air for a given output, the volume will vary but the weight will remain the same. It's just a lot easier to do everything by weight, otherwise you have to recalculate all the time for temperature variations etc.

Greg

[ToonRboy]

Right, adiabatic efficiency=thermal efficiency or absence of heat transfer. Chalk up another misused (or misspelled) acronym to the ToonR. V-trim really doesn't mean volumetric! How about just "efficiency"?I don't think you were really lost tho...

Quote:

It's just a lot easier to do everything by weight, otherwise you have to recalculate

[buzzed]

weight takes into account altitude, which depending on how 'on the limit' you are, can be important.

Update:
I pulled down both the twin spark block and the single spark block. It appears that they are almost identical. At the rear of the block there is a filled in section on the twin spark block as apposed to the single....but other than that they really appear to be very very similar. All the stiffening ribs are the same dimentions etc.

My plan going forward is to stick with the single spark engine. If and when I want to upgrade I can change the front chest and with a couple of mods, the twin spark head will drop on by the looks of it. The reason I dont do this now is I would have to change the inlet manifold flange and have a custom exhasut manifold built. Given I have all this already done for the single spark, I don't want to throw good money after bad. Anyway, it will be interesting to see the improvements along the way. Its no fun if you go to the best system up front...where do you go from there?!

Now that I have made this decision, I can go ahead and order my pistons and rods.

Anyone on hear reccomend a clutch up to the task, ie anyone got 400hp on the street and had a good experience with a sprung clutch?

[Greg Gordon]

400hp, I don't know...I have personally seen Performatek's street clutch (part number DDCD-8CF) hold 276rwhp. I will soon be testing it with more power on it. Andy at Performatek has others that can probably handle more.

Greg

[buzzed]

Just noticed there were more comments,

Biba - Love it, I'll make you a carbon fibre bonnet...no worries heheh. And as for the more of a challenge comment...challenge must be balanced with budget as per commetns above....one day! But let me know what is 'strengthened' in the twin spark block cause I cant see it!

Toonrboy....the compressor I am useing is 78 eff, yours is 80... I dont see how the math works out to a PR of 2? At 15 psi, the engine just does not flow enough lb/min

[Greg Gordon]

ToonRboy, I figured you just mistyped. I do it to I just wanted to clear that up because on a Roots or Lysholm blower volumetric efficiency is a big deal. If you don't get it right, you end up with a boost curve that's very steep. Of course this results in minimal low end boost, thus defeating the whole reason for going with these types of superchargers in the first place.

I am going to stay out of the turbo side of this discussion because it's really not my area of expertise.

Greg

[5yearplan]

weight is also important for figuring in Brake Specific Fuel Consumption which is an important tuning detail when it comes to making power, as well as retaining some semblance of gas mileage

[PSk]

Quote:

Originally Posted by Biba69 Personal comments: Strictly eyeball engineering but the TS block with its additional strengthening ribs HAS to be stronger than the Nord block. Also, the TS head HAS to flow considerably better than the 50's designed Nord head. Biba

[buzzed]

PSk,

On the subject of intercoolers, hard to say which is better, you would have to consider cooler effieicies based on heat soak etc. On the face of it, 2 seperate coolers will give you less heat soak, but prove a pain to package...not so sure it would weight anymore, actually for the same effieciency, it could come out on top.

Anyhow, I think I am resigned to water injection for the second stage and intercooling for the first.

As for the head, twin spark would be better for boosted application just as it is for na. Volumetric efficiency is a factor when considering the hp potential of the system. Eg, my calcs for VE for single spark vs twin spark my numbers increase from 370hp to 415hp all other things being equal when useing the better head. It's an estimate, but the point I make is that a better VE on a head healps boosted motors......kinda talks me into a twin spark head though hey?!....NO!....I must resist.

[5yearplan]

why dont you just get some mild head work done to the stock head?

[buzzed]

Well I have a set of high lift cams and I will port match the manifold, but that will be all for now. I'm trying to avoid a head recondition when the head is already in excellent condition. But yeah thats one way to get more 'free' hp without the inherent reliability issues of more boost!

[Greg Gordon]

I would use the Nord. Over here at least parts for it are much more common, plus it's head design looks like it was made specifically for supercharging. The twinspark may be stronger, I don't know, I have never seen one, however the Nord engine won't be the weak link in the system anyway, that will be the transaxle. I am also a little worried about Guibos with the Nord.

Greg