Giant Gauge Test - Part 1

The aftermarket automotive gauge market is booming. But which are the good gauges and which are the bad? We decided to find out. We employed the services of a professional automotive instrument workshop to test numerous gauges - including mechanical and electrical pressure gauges, mechanical and electrical temperature gauges, tachometers and voltmeters.

We've given a concise summary for each of the tested gauges - appearance, price, size, markings and accuracy.

Please note that all of the following gauge pricing is recommended retail, as supplied by the wholesaler.

Mechanical Pressure Gauges

Di Pricol 0-35 psi Boost Gauge

An alloy chassis gauge carries a similar appearance to AutoMeter, meaning it looks the goods, measures a practical and common 2 5/8-inch, and is side lit. Increments are at 1 psi with large numbering every 5 psi. Supplied with quality line and fittings. RRP: $109.15.

Conclusion: Medium to high priced gauge that looks great, and performs well with excellent accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
Di Pricol C303085	0-35 psi Boost	5	5.1	1.5
		15	15.5	3.3
		25	25.7	2.6
		35	35.7	1.9
		Average Error: 2.3%

AutoMeter -40Hg-20 psi Boost Gauge

Seen to be setting the standard, AutoMeter gauges are cosmetically attractive, and rely on an alloy chassis for durability. Boost gauge includes off-boost vacuum and boost levels at 5 psi increments. Supplied with quality fittings. RRP: $160.00

Conclusion: High priced gauge that looks great, yet performs at the lower end of the accuracy scale.

Gauge	Specification	Gauge psi	Reference psi	Error %
AutoMeter AU4401	-40Hg-20 psi Boost	5	5.8	11.6
		10	10.9	9.3
		15	16.3	8.5
		20	21.5	7.5
		Average Error: 9.2%

Specometer -30Hg-20 psi Boost Gauge

White faced, lightweight silver coated plastic construction, 2 5/8-inch boost gauge is available with coloured press-on bezels to radically change the appearance. Vacuum markings are set at 10 and boost at 5 psi, also with 1 psi increments. Side lit, comes with fittings and line. RRP: $67.00.

Conclusion: Medium to low priced gauge that looks good, however one can only hope was faulty as it accuracy was terrible.

Gauge	Specification	Gauge psi	Reference psi	Error %
Speco 537-03	-30Hg-20 psi Boost	5	5.9	17.9
		10	11.4	13.8
		15	16.6	10.8
		20	22.0	9.9
		Average Error: 13.1%

Pricol 0-30 psi Boost Gauge

Two inch black-faced gauge, steel chassis, small black bezel, side lit, 5 psi markings with 1 psi increments. Easily read, sturdy construction. Comes with line. RRP: $42.05.

Conclusion: Low priced gauge that looks agricultural yet purposeful, while providing exceptional bang for your bucks with excellent accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
Pricol 301524	0-30 psi Boost	5	5.1	1.5
		15	15.5	3.3
		25	25.8	3.2
		30	30.7	2.4
		Average Error: 2.6%

A'PEXi -760Hg-2.5 Bar Boost Gauge

Black faced 2 5/8-inch back lit gauge with silver bezel, metal construction, all fittings and programmable for maximum memory recall and peak required. Complete with warning light and of extremely high quality appearance. RRP: $350.00.

Conclusion: Super high priced gauge that looks fantastic and comes with very high quality fittings, and is the best performer of the boost range with almost perfect accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
A'PEXi A-54	50Hg -37psi Boost (-760-2.5 Bar)	0	0	0.0
		14.7	14.4	-2.0
		29.4	29.1	-1.0
		Average Error: 1.0%

VDO -30hg-25 psi Boost Gauge

Side lit black bezel, 2-inch, black faced dial with 10Hg and 5psi numbers, 1 psi increments. Metal construction. All fittings. RRP: $75.15.

Conclusion: Medium priced gauge with an acceptable appearance, while generally providing good accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
VDO 150077004	-30Hg-25 psi Boost	5	5.0	0.0
		10	9.0	-10.0
		20	20	0.0
		25	25	0.00
		Average Error: 2.5%

DiPricol 0-15 psi Fuel Pressure Gauge

Alloy chassis offering quality appearance, measures a practical and common 2 5/8-inch, and is side lit. Increments are measured at 1 psi with numbers at every 3 psi. Supplied with quality line and fittings. RRP: $98.75.

Conclusion: Highest priced mechanical fuel pressure gauge, however it looks great. It's interesting how most of the fuel pressure gauges performed poorly with most having between 7 and 10% inaccuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
Di Pricol C303010	0-15 psi Fuel Pressure	5	5.2	4.2
		8	8.5	6.5
		10	11.7	16.9
		15	16.4	9.3
		Average Error: 9.2%

Splitfire 0-100 psi Fuel Pressure Gauge

Alloy chassis, white face 2 5/8-inch gauge with 20 psi numbers and 5 psi increments. In standard trim has silver bezel, however example is fitted with purple bezel. Supplied with all fittings. RRP: $89.00.

Conclusion: Second highest priced fuel pressure gauge offers a great appearance, and the best performance of this bunch.

Gauge	Specification	Gauge psi	Reference psi	Error %
Splitfire C303085	0-100 psi Fuel Pressure	20	21.6	8.1
		50	52.0	4.0
		80	82.8	3.6
		100	102.5	2.5
		Average Error: 4.7%

Specometer 0-15 psi Fuel Pressure Gauge

White faced, lightweight silver coated plastic construction, 2 5/8-inch gauge available with coloured press-on bezels that heavily alter the appearance. Increments are set at 1 psi with readings at every 3 psi. Side lit, comes with fittings and line. RRP: $65.70

Conclusion: Low priced gauge looks good, with middle of the road (for this group) accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
Speco 537-07	0-15 psi Fuel Pressure	5	5.4	8.0
		8	8.5	6.5
		10	10.8	8.0
		15	16.0	6.8
		Average Error: 7.3%

Pricol 0-16 psi Fuel Pressure Gauge

Two-inch black faced dial with 2 psi increments, white markings. Side lit, easily read, good quality construction. All fittings and hose. RRP: $59.30.

Conclusion: Lowest priced mechanical fuel pressure gauge on test with an acceptable no-frills appearance, but with almost 10% overall inaccuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
Pricol 300543	0-16 psi Fuel Pressure	4	4.6	13.8
		8	8.9	11.0
		10	11.6	16.0
		16	17.3	8.1
		Average Error: 9.7%

VDO 0-30 psi Fuel Pressure Gauge

Side lit black bezel, 2-inch, black faced dial with numbers every 10 psi, and with 2 psi increments. Metal construction, good quality. All fittings. RRP: $75.15.

Conclusion: Medium to high priced with acceptable appearance, however it showed poor accuracy for a gauge with such a solid reputation.

Gauge	Specification	Gauge psi	Reference psi	Error %
VDO 150077011	0-30 psi Fuel Pressure	5	5.0	0.0
		10	9.0	-10.0
		15	12	-20.0
		20	18	-9.0
		Average Error: 9.7%

VDO 0-100 psi Pressure Gauge

Side lit, black bezel, 2-inch, black faced gauge with white numbers incremented at 20 psi, with 5 psi increments. Metal construction, good quality. All fittings. RRP: $75.15.

Conclusion: Medium to high priced gauge which like most VDO items won't set the world on fire with its appearance, however it delivered better than average accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
VDO 150077027	0-100 psi Pressure	20	21	4.9
		50	20.8	4.2
		80	80.1	1.1
		100	99.9	-0.1
		Average Error: 2.6%

DiPricol 0-200 psi Oil Pressure Gauge

Alloy chassis white faced gauge, 2 5/8-inch, side lit. Increments measured at 5 psi with numbers initially every 20 psi then at 40 psi increments. Supplied with quality line and fittings. RRP: $103.95.

Conclusion: Highest priced mechanical pressure gauge in this group, it's nicely packaged and offers the best performance of the group.

Gauge	Specification	Gauge psi	Reference psi	Error %
DiPricol C303054	0-200 psi Oil Pressure	40	40.8	2.2
		60	61.6	2.7
		80	81.9	2.4
		100	101.8	1.8
		Average Error: 2.3%

Splitfire 0-100 psi Oil Pressure Gauge

Alloy chassis, 2 5/8-inch white face with 20 psi readings and 5 psi increments. Side lit, standard with silver bezel, example fitted with gold bezel. Supplied with all fittings. RRP: $69.00.

Conclusion: Competitively priced given its good looks; not quite up there in the accuracy stakes.

Gauge	Specification	Gauge psi	Reference psi	Error %
Splitfire	0-100 psi Oil Pressure	20	21.6	8.1
		50	52.1	4.2
		80	82.7	3.4
		100	101.5	1.5
		Average Error: 4.3%

Specometer 0-100 psi Oil Pressure Gauge

White faced, lightweight silver coated plastic construction, 2 5/8-inch gauge also offered with coloured press-on bezels for improved appearance. Increments set at 10 psi with numbers every 20 psi. Condensed scale is a little hard to read. Side lit, comes with fittings and line. RRP: $61.65.

Conclusion: Second lowest price but with quality appearance and generally very good accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
Speco 537-16	0-100 psi Oil Pressure	20	21.5	7.4
		50	50.6	1.2
		80	79.9	-0.5
		100	101.6	1.6
		Average Error: 2.6%

Pricol 0-100 psi Oil Pressure Gauge

Two-inch black faced dial with large 25 psi increments, and numbers at 50 psi, white markings. Side lit, good quality construction. All fittings and lines. RRP: $59.30.

Conclusion: Cheapest of the group, the Pricol continues the tradition of offering acceptable appearance with reasonable accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
Pricol 300542	0-100 psi Oil Pressure	20	19.1	-4.5
		50	48.8	-2.3
		80	78.0	-2.5
		100	92.8	-.7.2
		Average Error: -4.1%

Electrical Pressure Gauges

Specometer 0-100 psi Oil Pressure Gauge

Easily read white faced, silver plastic construction 2 5/8-inch gauge. Increments set at 5 psi with numbers every 20 psi. Side lit, comes with fittings and line. RRP: $93.65

Conclusion: Low priced electrical oil pressure gauge delivered fairly good accuracy at an affordable price.

Gauge	Specification	Gauge psi	Reference psi	Error %
Speco 537-16	0-100 psi Oil Pressure	0	-3	0.8
		50	46	-8.0
		100	98	-2.0
		Average Error: 3.6%

A'PEXi 0-118 psi (0-8 Bar) Oil Pressure Gauge

Black faced 2 5/8-inch back lit gauge with silver bezel, metal construction, all fittings and programmable operation for maximum memory recall and peak required. With warning light and of extremely high quality appearance. 0.1 bar increments, 1 bar number spacing. RRP: $350.00.

Conclusion: Super high price, brilliant appearance yet strangely it suffered a little by not having great accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
A'PEXi A-56	0-118 psi Oil Pressure (0-8 Bar)	14.7	15.4	5.0
		58.8	61.0	3.8
		102.9	108.0	5.0
		Average Error: 4.6%

A'PEXi 50Hg - 30 psi (-760-2 Bar) Boost Gauge

White faced 2 5/8-inch back lit gauge with silver bezel, metal construction, with all fittings, non programmable. Has increments of 0.1 Bar, and 0.5 Bar numbers. RRP: $280.00.

Conclusion: The non-programmable A'PEXi is also quite expensive but without the bells and whistles, still looks brilliant while offering acceptable accuracy.

Gauge	Specification	Gauge psi	Reference psi	Error %
A'PEXi A-50	-50Hg -30 psi Boost (-760-2 Bar)	0	0	0.0
		14.7	13.5	-8.0
		29.4	29.1	-1.0
		Average Error: 3.0%

Next week: tachos and temperature!

Contacts: (Contact the following distributors for local supply details)

VDO:
VDO Australia
1800 335 282.

Specometer:
Speco Thomas
03 9555 7244.

A'PEXi:
Access
03 9873 0133.

Splitfire:
Lynx Corporation
0500 80 20 30.

DiPricol:
Performance Wholesale
07 3808 1986.

Pricol:
Hardiman Auto Supplies
02 9771 5877.

Gauge Testing The decision to request the services of Howard Instruments, a specialist instrument maker with offices in West Heidelberg and North Geelong in Victoria, was too easy. I mean with 30 years experience, the company has as much - if not more - cred than any gauge repairer in the country. It's also worth noting that while most cities have specialist instrument repair companies, few have the experience of Howard's. The company can repair, rebuild or recalibrate any gauge you care to name. What's more, they offer retail sales on gauges at very competitive prices. Brands on offer include VDO, AutoMeter and others. "Speedo calibration is a huge area of concern, with so many people simply accepting that a wheel and tyre change alters speedo accuracy, and doing nothing about it," explained Roger Howard. "Unfortunately, the Australian Design Standards allows for a speedo accuracy of + or - 10% and a + or - 4% inaccuracy for distance. The consequences of this leniency is that you may think your speedo is somewhere near being correct, when in fact it may be 10% out and get you booked for speeding. And we're talking new cars here...." "You simply shouldn't have to put up with incorrectly calibrated speedometers. There are two ways we go about calibrating a speedo. The first is if we have the vehicle at our disposal we can calibrate the unit itself or fit an inline ratio box. If the speedo has been removed from the car, we simply need all of the pertinent information to perform the calibration." Roger can provide a wealth of information.... in fact he can talk the leg off a table. In other words, if you have a problem, he should be able to help. During our time together he showed some concern over how many people fit fuel pressure gauges on a cowl panel or even inside a car. He noted that in many cases the neoprene diaphragm in an electrical sender stretches, resulting in inconsistent figures. More worrying though is the integrity of a mechanical sender line. If one breaks, fuel can spray over the windscreen causing loss of vision or worse, a fire can result. Roger suggested that manufacturers are not aware of the compatibility of their gauges with all makes and model of vehicle. And all too often someone will buy a tacho or the like and irrespective of their attempts, they simply can't get it to work properly. He cited the VN Commodore as an example whereby the signal strength and type with the factory tacho means that adapting an aftermarket item can be a nightmare. So don't ever take anything for granted. Get some good advice. Even though there aren't many instruments makers around, it's worth finding one and asking which gauges are most suitable for their application. Contact: Howard Instruments: West Heidelberg 03 9457 4755. North Geelong 03 5278 7822.