Gtv-ts - Page 13 - Alfa Romeo Bulletin Board & Forums

  #181 (permalink)  
Old 04-29-2012, 06:40 AM
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That is very interesting using the phone ap for a crude dyno. Never tried that before, I have heard that G-tech is very good, but never got around to shelling out for it.
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  #182 (permalink)  
Old 04-29-2012, 07:09 AM
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The torque curve and the HP curve always cross at 5250 it's to do with the math . hp = (torque * RPM) / 5250 .
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[URL="http://www.alfabb.com/bb/forums/engine-conversions/172068-building-200hp-twin-spark.html"][B][SIZE="2"]Building a 200 HP Twin Spark[/SIZE][/B][/URL]
[SIZE="2"]David Munro[/SIZE]
Toronto ON Canada
1969 Spider JR Twin Spark
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  #183 (permalink)  
Old 04-29-2012, 08:43 AM
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Right that's why the output of the app is weird.
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  #184 (permalink)  
Old 04-29-2012, 11:12 AM
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Here is a quick comparison between the G-tech, iPhone, and a rolling dyno:
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  #185 (permalink)  
Old 04-29-2012, 06:24 PM
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If you look for the crossing point, you have to look left at the HP (or even KW) scale and right for the torque scale. If they are not 1:1 HP:torque, they cant cross at 5250.
With this dyno sheet at 5250 I see the HP are 116 and torque can be read 116 Ft.Lb.

So for me this is OK
.
The soft dynos are very exact. As they measure wheel power, hotter transmission oil, wind, any change of weight and other factors give variations. Done correctly under best conditions with the same weight of the car and weather, they give as good or better repeatability as a rolling road dyno.
The graph you get will tell you if everything was OK, as it should be even and show no jumps.

What modern "real" dynos can do is to add the drag of the transmission, to get crank HP, but exactly this is the cause for the differences in HP numbers found with "friendly" and "conservative" dynos.
Kiddies have a tendency to go and pay for the dyno giving the "best" numbers in town, so it is not the measurement technique that makes the difference, but the trim factor the owner programs into the machine.
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  #186 (permalink)  
Old 04-29-2012, 07:53 PM
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Sorry I should have had a coffee before I posted .

Or read you post more carefully .
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[URL="http://www.alfabb.com/bb/forums/engine-conversions/172068-building-200hp-twin-spark.html"][B][SIZE="2"]Building a 200 HP Twin Spark[/SIZE][/B][/URL]
[SIZE="2"]David Munro[/SIZE]
Toronto ON Canada
1969 Spider JR Twin Spark
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  #187 (permalink)  
Old 06-08-2012, 06:04 AM
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Life has been hectic and summer has arrived so I have had little opertunity over the last few weeks to play with the car. I finally got around to finishing the last set of tweaks to my carb setup.

As some of you might have seen in my other posts I had to make a carb support plate for the TS intake manifold and then modify the strut. Was trying to eliminate the effects of the motor vibration and jittery carbs.

I decided, after getting the carb support stuff sorted, to try the longer velocity stacks that came with the webers as opposed to the ones I got with the pipercross filter.

I was draging my feet on getting the Uni filters because I ultimately want to end up with a closed airbox. But after two weeks of not getting to drive the GTV I said enough is enough and ordered the Uni filters from Charlie over at Spruell.

Last night when I got home from work I installed the filters and took her out for a test drive. WOW what a difference. There seems to be a lot, well noticeable, torque increase through out the power band. I was very impressed with the difference.

No Dyno curves at the moment as I had to get a new phone two days ago and I did not have a chance to configure the app until this morning.

I will post pictures and the curve as soon as possible. If anyone out there is running the stubby trumpets change them now!!

Regards,
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Last edited by Seabird; 06-10-2012 at 05:25 PM.
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  #188 (permalink)  
Old 08-09-2012, 11:59 AM
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Miguel, perhaps I've missed something, but have you installed the new cams yet? I know your main concern has been with the Webers.
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  #189 (permalink)  
Old 08-09-2012, 12:56 PM
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Nope been too lazy. Sort of.

I have not made the time commitment to do anything with the GTV lately; other than drive it

I have been swamped at work so I have not been able to drop it off at the shop. I am getting one of the local Alfa specialists to do the cam swap. I don't have access to a shim kit and it seems to be more daunting of a job than I care to tackle at the moment.

I had her out last night for about a 45 min drive and was loving it. I have been driving a rusted out old El Camino (67) the last week or so as a daily driver and what a difference getting back into the GTV. The clutches alone are a night and day. On the GTV I used the full Tilton set up sold by Spruells and the Camino has a mechanical clutch, lol. I was pulling out of the garage and chirped the tires. The Tilton actuates the clutch in about 1/8" of travel; which I am a fan of just needed to get the muscle memory back. When I dropped her into the first tight turn at speed a grin as wide as the grand canyon spread across my face.

The El Camino is great too just in a completely different way. My brother picked it up about two years ago out from under an oak tree, not running, for $700. After a carb overhaul, a battery, and a new tire he had it on the road again. Fast forward six months and the starter died along with his interest to drive it. Last week I got tired of seeing it sit so I swapped the starter, 44$ and a hour of my time and she was back on the road. I need to make sure I have my tetinous shot up to date if I am going to keep driving this rusted rod. I guess I am a gear head

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  #190 (permalink)  
Old 08-10-2012, 12:22 AM
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Quote:
Originally Posted by njh1964 View Post
Hi Miguel,

Sounds like we both still have a bunch of questions on the VVT.

So far, my understanding is that, with the VVT solenoid off, the cam is in a retarded position. I also understand that this helps with emmissions and fuel economy. When the VVT solenoid comes on, the cam is advanced for improved performance.

The standard Twin Spark Bosch Motronic ECU apparently activates the VVT solenoid based on a combination of throttle position (ie load), and when the engine is operating within a certain rev range. I undertand that the beginning of this range is between 1,300-2,000 RPM at the lower end, and perhaps 4,500-5,000 RPM at the upper end?? Outside of that rev range window, and without significant load (ie mashing the loud pedal), the VVT is off.

One school of thought in relation to running a Twin Spark on carbs is to run a constant 12 volt feed to the VVT solenoid when the engine is running (ie from the ignition switch circuit). I guess this would mean the cam is constantly advanced, at least when there is sufficient oil pressure in the engine to make this happen (ie the VVT solenoid apparently enables engine oil pressure to hydraulically advance the cam).

Another school of thought is to fit an RPM window switch which would power up the VVT solenoid when the engine is running within a defined rev range (eg 1,300 RPM to 5,000 RPM). This is still a compromise as there is no load/throttle position control factored into the equation.

I'm currently thinking that an RPM window switch might be the best option, but I'm also thinking that a dash mounted by-pass switch might be a useful addition. For example, when cruising along and not looking for power, a switch to disable the VVT solenoid (ie by-pass the RPM window switch) and retard the cam for better fuel economy might work OK.

Still seeking input from others who have already tackled this issue.

Regards,


Nick
When I fitted a T/S to my 67 stepnose 3 years ago this is what I did (hard wired a switch on the dash to operate the VVT) - I call it the loud switch! With a pair of 45s the induction note changes remarkably (in the 'on' position) & the throttle response is markedly improved. I tend to turn it to the off position for starting the engine (retarded inlet cam) then flick it on as i pull away (and then tend to leave it on permanently). Incidentally, this was all a bit of a trial (& worked so well I've left it alone, though the engine is now on its last legs - it had been sat outside a friend's back door under a cover for several years!) - I used the original 75 (Milano) ECU & loom but by fitting the carbs the wiring to the injectors became redundant. The cps is used & a tps fitted to the carbs (the Alfa loom has a connector that fits). The connections are also there for the VVT solenoid, but I found that because the AFM wasn't used, the ECU didn't activate the VVT, hence the hard-wired switch. The rev limiter doesn't seem to get activated either - I'd always assumed this would have been a signal cut-out to the ignition side but maybe it's to the injection side....?
The 45s don't bog down (I've experienced this on a Nord & would normally advocate 40s on anything but a race engine), but I think the ones I picked up were already jetted for a T/S. It's a stock T/S other than the carbs & tubular exhaust manifold (that's not to say it's a 5-minute drop-in, plug & play conversion though!).
Hopefully that's of interest.
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Last edited by ianellisalfa; 08-10-2012 at 01:02 AM.
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  #191 (permalink)  
Old 08-10-2012, 06:04 AM
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There is a plethora of ways to actuate the VVT on the TS as can be found here on the forum. Some more, some less complicated. Wiring it to the shift light trigger from a engine management cpu is easy enough if you have one to start. If you don't there are several rpm based switches out there that can take the place of the cpu. And if you really want to get crazy with the logic switches there are a number of threads that are working out a system for this too.

I am not a fan of the manual switch idea; I just don't want to have to think about reaching over and flicking a switch when I am rowing the gears. That seems like way to much work. And dangerous too.

Where I am not utilizing the VVT correctly is above 5500 rpm it seems. According to some the VVT should shut off over 5500 rpm at WOT. In truth I don't spend that much time over 5500 rpm at WOT to justify adding another system to the GTV.

Its like talking about putting a turbo charged v-6 3.0 in her, or even a v-8 as some have done to spiders. If I want to hit 140 in under 15 sec I'll just take the vette out. But there is a reason why the GTV get 2-3x the miles that the vette gets
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  #192 (permalink)  
Old 10-16-2012, 01:02 PM
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Quote:
Originally Posted by Biba69 View Post
Miguel, perhaps I've missed something, but have you installed the new cams yet? I know your main concern has been with the Webers.
In answer to your query, Friday. Looks like Friday I am going to take the GTV over to Stephen's Alfa so Eddie can do the cam swap.
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  #193 (permalink)  
Old 11-11-2012, 12:21 PM
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75ts install giulia super

about 7 years ago I fitted a standard blueprinted 75ts engine with dellorto 45s with a 38chokes homemade inlet manifold (original injection inlet with welded extensions and mounting flanges) long inlet trumpets and pipercross airfilter ,Jim Steck nissan distributor,vvt operating from about 1500rpm onwards ,OKP alloy flywheel electric fuel pump etc .I had the car jetted on a rolling road with timing and fueling set by a very experianced guy who only tunes cars with carbs to 155bhp at the flywheel It drove great, smooth and torquy. I drove the car a few years later and it had its inlet manifold replaced to the one that the likes of alfaholics sell ,It had lost some of its low down torque but still managed to keep up with some so called race cars on the straights .The car is still running strong today now on its 3rd owner with a lots of miles covered trackdays and now a few rallys all without breakdowns.
I am building a 1974 Giulia super 1300 with a standard ts engine but Im going to run with motronic 4.1 with lamda sensor a proper ducted/insulated and sealed air intake system to take affect of the air ramming effect , raising rate fuel regulator a thermal wrapped csc exhaust system, again a OKP lightweight flywheel I am expecting the same or more power out of this setup and this combo is plenty of power for everyday use and the odd trackday and better mpg.
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  #194 (permalink)  
Old 11-11-2012, 12:30 PM
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Hi Sparkyshep,
I think I drove the car with your old engine in the other day.... Did yours go to Edinburgh then back down to London? If it's the same one, a guy called Yushan bought it & transplanted the engine into his '66 Super (graphite grey with red interior - lovely car that I've looked after for several years) - great fun to drive but a bit lumpy below 3000rpm (cams?) & needs an LSD!!
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  #195 (permalink)  
Old 11-11-2012, 02:39 PM
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Hello Ian yep thats my old engine I have met Yushan at Shelsley Walsh hill climb ,He is a really nice guy also the prevous owner Ian from Edinburgh I did a track day with him at donnington .I expect the original car is needing some work now it was getting a little tatty round the edges but it had a really solid shell ,I bought that one in from france as a standard super it changed a bit over the years.I did ask about buying the old car back but it did not happen.
Im on a new project now a 1974 super have had to do a heap of bodywork and repairs as the car had been in storage for many years in a lockup in poole. I am not to obsessed with making show cars just solid engineering and i recon with the setup I am planning on using the car should be swift enough with a few mods i am not to worried about 200bhp ts engines as I cant run to that expence on my lowley auto electricians wage, good to hear its going well I see you have a green giulia is that a customers or your own car?? I plan to run my car down through the Stelvio Pass next summer if I get it done in time thanks Steve
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